I've tried exporting a character in NWN2 but I'm unable to select it when I go to start a new module with him. The only character I can find is my custom character at level 1, even though I've exported him at level 20.

I know there are two folders on my computer named "localvault." One of them is where GOG has it set up for its own use; the other is the old-school location that NWN2 would use if it were installed on its own. I've found the .bic files for my character in C:\Users\<me>\Documents\Neverwinter Nights 2\localvault and copied them to the new GOG-friendly location at C:\Program Files (x86)\GOG Galaxy\Games\NWN2 Complete\Localvault.

I still can't find that character even after several restarts of the game. Has anyone else had this problem? How can I fix it?

Thanks much!

Which module? It might not accept characters as high level as you want to import.

Or the exporting module could have some custom character haks, that you can't import in other modules.

Sorry. I forgot to mention that.

I built up my character in the other modules and now I'm trying to play it in the main campaign.

Main campaign is intended for a 1st level character. Some RPGs scale to your level, but AFAIK the main campaign does not. You would ruin any challenge with a high level character. A huge point of these campaigns is the rise to power from nothing. I mean you may as well just turn on invincibility/GOD mode if you are going to import maxed out characters.

I don't think it will block higher level characters, BUT characters higher than level 20 probably won't show up at all because those levels didn't exist in the original campaign.

Try starting a Mask of the Betrayer campaign and see if your character is visible there.

As a general rule for NWN games. Don't use GoG Galaxy anywhere near these games. It can do screw things with regards to save files.

If it is one of the races with full-level adjustments, i.e., Tieflings +1, deep gnomes +3, there could be some interference with how the game is reading the hit dice; check with a slightly lower level if you can. Importing <=20 characters should work in the nwn2 OC.