Since latest update, I cannot export large panorama files anymore

if you are using a graphics card, disable it in edit/preferences/use graphics processor.  that worked for me.

Thanks for taking an interest in this, GoldingD. I'll do my best to answer all of your questions as concisely as possible.

It's a stack of 90 photos. I shot 3 bracketed shots per perspective. So that's probably 3 rows, 10 columns per row, 3 photos per perspective at -2 0 +2. I'm shooting at 50mm f/11 with an R5 so it's a 45mp sensor. The slightly cropped pano is 30,156 x 13,884 (~397.6 megapixels). Well under the maximum size for Lightroom and Photoshop.

I did the merge in Lightroom Classic. No issues there. The only reason it went into Photoshop is that I wanted to remove the railing and clean up some branches. I was able to quickly edit a copy in Photoshop and yes it did save as a PSB. I didn't have a problem until I tried to export as a JPEG. (For some more context, I know all about max file sizes in LR having done many of my merges in PTGui when my panoramas get too large, but that wasn't the case here.)

My Camera Raw Cache is at 120GB. I could probably try bumping that up if necessary.

There's nothing inherently special about this panorama verses the ones I've done before.

So here is what happened next. I ran the export and went to bed. When I woke up, it was finished. So, it did finally do it,. Is there any way to get debugging information from Lightroom for what it is doing during the delay? I tried again this morning and it seems to be stuck again, so not sure how many minutes/hours it took to finally go through last night. It wouldn't bother me as much if the Task Manager showed it was doing something... but it's just sitting there. Haha.

Thanks again for your help and let me know if you need anything else from me.