First Door at the Solasan Temple appears to be permanently locked.

There's only the one locked door on the first floor of the temple, (which as you know you can only open after opening all the other ones in the temple even if you have enough of the shards.)

If you've already been there once, that's it.  Did you defeat the demon that time?  Did you open the sarcophagus?

The OP is talking about the entrance to the temple itself, the first door you open with shards.

I have never had that one re lock after getting in when I go out to get more shards but, perhaps repairing the game will correct it.