This is the common issue we see many times during hotfix installation.
In my case most of the times, hotfix was not detected AX model database due to hotfix already installed/present in the application.
Below MSDN blog will explain you the reasons behind for not finding the model database while installing a hotfix.
MSDN BLOG LINK – Thank you Prasanna Penumarthi [MSFT] for your post.
Note: You can also check hotfix KB is present/ not on the server control panel. If the hotfix KB present means, hotfix was already installed. This step doesn’t mention in the blog.
Path: Start>>RUN >> APPWIZ.CPL>>View Installed Updates
“ Yours, Ravi Theja Madisetty ”