Merchants do not restock empty soul gems if they acquire filled ones.
Merchants that restock soul gems (Fadase Selvayn in Tel Branora and Elbert Nermarc in Craftsmen's Hall in Godsreach) limit their restocking supply every time they obtain a soul gem of the same type as the one they restock. For example Fadase Selvayn has 5 common soul gems for sale, but if she acquires a common soul gem with a scamp soul, her restocking supply drops to 4. If she is acquires 5 or more she will stop restocking empty ones entirely until the filled ones are sold. The issue is also referenced in a reddit thread here https://www.reddit.com/r/Morrowind/comments/49x5h2/anyone_run_into_a_inventory_bug_with_elbert/ along with another possible bug.
I've attached a save file that makes it easy to reproduce.
#1 Updated by Jeffrey Haines 11 months ago
I couldn't get your attached save to load btw, refer to attached image for specific error
I made a recording of the issue: https://www.youtube.com/watch?v=CTSvG9pyiXE
I do confirm the issue, restocking is reduced by 1. In the video I buy 6 common soul gems from a stock of 10. I sell the merchant 1 soul gem with a rat soul. She then restocks up to 9 soul gems.
I also notice another potential issue. Are merchants supposed to restock soul gems as soon as you talk to them again? I thought you have to wait some time. This issue is potentially a regression!
On another note, the not restocking issue may be expected behavior. I mean if a merchant has 10 (9 empty + 1 full) why does she need to restock her empties to 10? She has 10 soul gems.
#2 Updated by Michael Papageorgiou 11 months ago
I can't imagine why the save doesn't work for you.
Regarding instant the restocking, this is how vanilla works for better or worst. Vanilla has even worse exploit potential on this. See #2473
I imagine the source of the problem being that internally the difference between an empty and full soul gem is not taken into account at least by the restocking algorithm.
The problem with this issue is that you may want to sell soul gems to the merchant, without them clogging your supply of empty ones, which is a pretty rare service.
#4 Updated by Jeffrey Haines 11 months ago
I hesitate to comment on the issue of the save file. AFAIK all saves should be transferable between at least the latest and last two versions. I could be wrong though.
I guess this bug is a matter at how you look at it. I hope others can weigh in.
I do think there exists an issue where items are being restocked every time you speak to the merchant. This would definitely be counter to the behavior anyone expects in Morrowind.
How does vanilla Morrowind handle the soul gem situation?