I don't see any commonality of items that have this issue but once it starts it usually continues until I get out of the auction UI completely and go back in. It looks like the items will list but they don't.

(from the discord)
😨 Blizzard have modified the AH in this week's realm restart to cause mass posting/searches to fail or take forever. This was an intentional change. See https://us.forums.blizzard.com/en/wow/t/auction-house-much-slower-today/556722/13

This isn't new, it's been going on for a week or two but I was waiting for this reset to see if it improved things, if anything it's worse now but the issue was happening before today. Also, in many cases I'm just listing a single item (say, a boxed pet), not anything in bulk.

Try running /auctionator config feature_selling_1 to disable the auctionator undercut and default duration setting code, that usually resolves the issue.

As of the latest alphas we no longer modify the "Sell" tab, and encourage users to use the "Selling" tab; so this bug no longer applies to auctionator. If this issue pops up again with the "Selling" tab please report it in a new issue.