Catalina Messages fail when sending file from external drive, fixed on Big Sur?

Hi all, I have been plagued with issues sending images on the Mac Messages app. Texts send ok but images generally fail. At first I thought it only happened when sending to a group comprising both iPhone and Android recipients. However right now I have seen images timing out and failing to send to a group of all iPhone recipients and then a group of just myself.

Having researched this, I find that the issue is apparently due to the image being sent residing on an external drive. There’s an Apple support thread going back 2 years about this. Recommendations include removing Library/Messages .db files, but that deletes your entire chat history so for me it’s not an acceptable solution. I found that to get an image from my internal disk to send, I had to first delete all the stuck attempts to send images from my external disk.

Allegedly the issue is resolved in Big Sur. I’d like to ask if anyone has experienced this issue or resolved it, either by updating to Big Sur or otherwise. I feel it’s a little early to do the Big Sur update as it reportedly hasn’t been problem free but maybe it’s time?