the Devs have been made aware of this issue for ages, we (users with SSDs) are all waiting on a fix.
it happens in CC and DF and comes and goes depending on software versions, motherboard brands, SSD types and all those combos of each.
since going to SSDs I've used different brands and types and CC and DF detection has been hit and miss.
until Piriform works out a reliable method of detection, perhaps a manual override where the user tells CC or DF the drive types would be a good, temporary work-around.
Another upgrade and STILL CCleaner is incorrectly identifying my laptop 2.5" drives as SSD when THEY AREN'T!
So I'm still using 5.29! Every time I upgrade, test the new release, uninstall, re-install 5.29 - it was working then, so you changed something and broke it!