I'm testing Mojave at home and I have many of my iMovie projects held on my NAS contained in APFS formatted Sparse Images (not sparse Bundles, or DMGs) that won't open in Mojave (10.14.5), but will open fine in 10.13.6. The issue is that trying to open one of these GTP/APFS formatted Sparse Image files results in a message that says "no mountable filesystem". I first thought it was something I was doing, but I can recreate this with the following steps on two different installs of Mojave: 1. Use Disk Utility to Create new image (File->New Image->Blank Image) 2. Specify The Following: (Save As: name of containing file, Format: APFS, Image Format: Sparse Bundle Image) put it on your desktop for easy locating in the next step 3. It will create the containing file and auto-mount it.. Simply unmount by dragging the image mount to the trash can. 4. Copy (drag) the Image File (.sparseimage) over to an AFP or SMB share 5. Double click to re-mount the image (over the network - given its on a network share now) 6. Will see error about no mountable filesystem. If you change any of the following, it all seems to work over the network: A. Format the Sparseimage as HFS+ instead of APFS B. Use a "Sparse Bundle Disk Image" (its a directory of files, instead of a single file) C. Use a "read/write" disk image (a thick allocated DMG file - no space saving) This seems to be some sort of limitation (or Bug) in Mojave (the exact same steps below will work fine in High Sierra (10.13.6) Can any one else confirm they are seeing this same behavior in 10.14.5?