Sync Fail with old game

Before you make any further attempts, please note down or screenshot your original player ID on the old iPad.

Since you have not mentioned anything about email registration, I assume this method has not been tried.  So we can give this a go first,  

On your old iPad, start PVZ2 and from the main menu, click the cloud button, click register and register your email to your account (you will also get 100 free gems with the first time register). 

On your new iPad, repeat the same registration using the same email address and you will be given a code to verufy you are the owner of the old account, once this is done you will get an ID conflict messgae and be given a choice to restore your old account onto the new iPad.  Please make sure you select the old one with your original progress and NOT the new one as the wrong ID is selected here, your old data will be overwritten. 

Once the old account is loaded, you can then check if the data (your game progress, items and in game currencies are correct, if not, then you need to go back to your old iPad, try watching an ads for gems or coins (so the amount is increased) and then do the ForceSync Player data option to update your local data to the server.   Once this is done, do the force sync again on the new iPad and see if the new amount of gems (or coins) matched. If so, then everything is good, if not, you will need to contact EA Help Center and open a new case of 'Missing Content' for further assistance.  

As you explained, I performed the registration on both iPads with the same email (both successful).
However, in neither iPads I was prompted with a conflict this time, despite refreshing the app.

the old one still preserves its data while the new one has no original data.

What do you advise me to do ?

Thank you for the feedback.

Since the recovering failed on the new iPad.  The obvious 2nd option is to delete the PVZ2 App on the new ipad and perform a new installation of PVZ2 and then run the email registration again.  I am not sure whethr or not the game center is interferring but you might want to run it with and without to see if it makes any differences.

Another way to check whether your saved data is working is to try and do a fresh install of PVZ2 on another (3rd) device, it does not even have to be on IOS, and then try to go through the email registration and see if this works.  

Thanks for your answer, 

However, despite applying what you proposed the issue still persist.

What do you advise me to do ?

Did you try to do a fresh install of PVZ2 on your phone (as a third device) to see if the account is recovered correctly?  

Yes, sadly the problem persists 

@ES-MajAlB-124   I have a suspison your old iPad is not saving its update to the server or saved to a wrong account.

Could you provide a little more details on your problem please?

1) What items are showing up on the old ipad but not on the new one?

2) Is the same player ID showing up on both iPads?

3) A quick sanity check please if May.  Please note down the gems count on both ipads, then watch an ads for gems on the old iPad, does the amount increase by 3?  

4) If so, could you try doing a force sync on the old iPad.   Once this is done, do a force sync on the new iPad.  Does the gem count increase by 3 on the new one?  

Certainly, I appreciate your guidance on the issue :

1. On the old iPad, I can see all the progress – this includes all the worlds & levels defeated, plants acquired, and counts of gems and candies. Unfortunately, none of this progress is reflected on the new iPad. (Exception upon download where a confict prompt pop up and shows the correct #of plants, candies and gems with the correct ID)s

2. Yes, both devices display the same player ID.

3. On the old iPad, the gem count is 239, whereas on the new one, it stands at 100. After viewing the ad and subsequently refreshing both games, the count on the old iPad increased to 242, but the count on the new iPad remained unchanged at 100.

4. Given that the entire game progress seems to be at risk, I'm concerned about whether a force sync would be the most suitable solution. Would you recommend any alternative measures?

Thanks for the reply.  What is most important now is that you do not do further tests on the old iPad since it still holds the correct progress and I recommend to back up that data if you can.

Now lets look at the information you have provided.

Referencing to point 1, I am assuming when the conflict prompt shows up on the new iPad , you have selected the old ID to recover your original account, so in theory the correct number of plants, mints (candies), gems should be loaded.  It is obvious this section has gone wrong, at a wild guess, it could be Game Center is interfering with the loading, maybe you can try delete the game again on the new iPad (at no risk since that is the wrong one anyway) then disable Game Center before re-install the game and see if the same ID conflict is showing after email register, if the old original ID with the correct progress is showing, please take a screenshot of it for your own record as you might need it when liaising with the Help Center Advisor. (please do not post your ID to the open forum).  Try complete the installation and see if it is still showing a wrong progress, if so, then you best option is to contact the Help Center by clicking the link at the bottom of this page and open a new 'Missing Content' case.     

Referencing to point 2, I have a strong suspicion somehow the new iPad is paired with or linked to a wrong save file from the server, this is why any changes either increases or decreases in the gem count in point 3 are not reflected.  Fault like this is not fixable by us players and it will required someone (such as a help center advisor) who has access to the the server to correct the error.

Currently, I think there is a long queue for reaching an advisor so please be patient but persistent, you have a much better chance to get your account recovered than other less unfortunate players who have no knowledge of their original player ID.  

Good luck.