I recently rebuilt my DAW and updated DimPro to 1.5 and it doesn't see DimPro installs in projects. I reinstalled 1.2 thinking I'd just upgrade it again but 1.2 recognizes itself in projects, 1.5 does not. I seem to recall some hubub about this when it came out. Is there a trick for getting this to work?

If the DimPro 1.2 instances are DXi, they will not be seen by DimPro 1.5 which is VST only. There is no way that I know of to get the projects to see a VST version where the DXi synth was originally used.

Then when I run the 1.5 install will it kill the 1.2 dxi?

Can't say, I have not used the DXi version in years. I do recall a thread or two reporting being stuck at 1.2 because of reliance on the DXi version.

The 2 different types will co exist