I did uninstall first. Installed fresh. Was 2.87. I started DMD2, it asked for update. I confirmed. Went into Settings … version still 2.87. I guess it is 2.88 now, but showing wrong/old version number?
Tried the update process on my Garmin Tread and it updated perfectly to 2.88, if I go to DMD2 global settings and scroll down it reports 2.88 installed.