Just ignore the Warning when selecting "Back-Up"
Shrink - will - Compress to the required 4.36GB - no problem
It's one of those - Shrink needs an Update - things
I've received the same Issue - from quite a few of the Newer Releases
All Resulted in a Perfect 4.36GB Back-Up
Just Ignore it - Shrink will compress it
It is a Completely False Report/ Warning