Friendship level will not increase

Hi! I've recently started experiencing a bug where my friendship level between sims will not increase no matter how many friendly interactions I have them perform, while the romance level has no issue increasing. 

I've scrolled on forums to try to find a solution and have tried everything i've seen so far - the modifyrelationship cheat, resetting sims, exiting out of household and coming back, deleting cache - but I am kind of at the end of my rope, especially because I'm not very familiar with the ins and outs of cheats and have no cheat mods.

In case it is of any help, I do have cc and mods, though the only mods I have are the Lumpinou and Pandasama pregnancy and birth mods.

Does anyone have any idea on how I can fix this? Thanks in advance!