Scratch disk not recognized

My LaCie, 2019 6TB external hard drive suddenly is not available on the scratch disc list in PS. It was working fine while creating animation. There is 2 TB available, it is journaled and has been declared ok by disk utility.
I am hoping it has nothing to do with my Mac OS which is running Ventura. I understand Sonoma can cause serious issues with Corel Painter, my default drawing software, so needless to say, I’d rather not upgrade.

Thanks in advance if anyone has an answer.