I followed Parallels' suggestion to reclaim 45GB of disk space and ended up with a corrupted Parallels Data File that cost me upwards of GBP 350 to have fixed. If I felt I had a chance of recouping that from Parallels, I would. In the meantime, I urge company to withdraw that faulty reclaim disk space function - and users should avoid it at all costs. (Latest MBP running Mojave and Parallels 15)
You know what...all my problems started when I clicked on Reclaim Disk Space about 2 weeks ago. This was when I was running Mojave and PD15. Upgrading to latest Catalina did not solve the problem. Unbelievable...
I was able to use Time Machine and thankfully I had a backup from October 1. I had to copy the entire VM from an external drive to my internal drive. I will never touch the reclaim disk space button again unless Parallels makes it clear it is safe to do so...