mikelikes

Thats because I didn't include the 64bit compiled version in the download I will add it as soon as I get home from vacation (in about two weeks)!

I posted a release a freshly compiled version (https://github.com/mikelikes/Telemachus/releases/tag/v1.5.2-ksp1.3). I made no code changes to the existing project, and didn't test this through! But maybe it helps you get Telemachus running on your machine. Also, try to use Telemachus on a fresh install to check whether the problem really is with the mod.

I compiled the code against KSP 1.3, both 32 and 64 bit and on both right clicking is working fine. Which version are you using?