I bought a 2019 iMac with a Fusion drive. In the next major update (High Sierra), Apple switched to APFS, which has issues with Fusion drives. It often shows

I bought a 2019 iMac with a Fusion drive. In the next major update (High Sierra), Apple switched to APFS, which has issues with Fusion drives. It often shows as having no empty space, even with 40% empty. Much, much worse, it stops writing to disk without giving any indication (the non written items show in finder, etc.) - for some ten hours or more - and then suddenly crashes and you find that the entire days worth of work is completely gone. Not on disk, not on external backup, not in Time Machine. This happens EVERY DAY, at least once a day, when using heavy programs such as Photoshop. There are many threads about the issue, and the only solution is to get a new non-Fusion drive and copy over everything. Much easier said than done. I cannot even begin to describe how much aggravation Apple has caused, and how little faith I have in them testing their upgrades. And of course, the whole play with searching my hard drive for something their algorithm thinks goes against my local government [which plays for keeps, thank you] - doesn't help.