Lightroom 7.0 (cloud-based) edited HEIC files not caching

Lightroom 7.0 cloud based on M2 Macbook Air (Sonoma 14.1) with hundreds of gigabytes of photo cache space; cannot scan through edited HEIC photos - there is a several second delay on each photo as previous edits are applied. Exporting original file to full size 100% jpeg is, of course, 4 times larger, but scanning is OK; Seems like edited views of HEIC photos are not being saved. Any ideas?