It's the same project... I can't understand what may be wrong. I can't reproduce at all! I tried changing various Reaper preferences but always no problem..
BTW, the sends from another track (in your project tr1) make no difference. The IR is captured inside the selected track. Sends from other tracks, send to master or not, etc do not make any difference.
Does the same happen with a new project? Using a different plugin?
Can you test in a fresh portable install?