We've received a few similar reports. If this occurs again, could you send us a sample (a snapshot) of Path Finder process in a separate file? This will enable us to analyze what happens with the application. Here's how to get it:
Open Path Finder and reproduce the problem. If the problem is dynamic (e.g. unexpected action result), please try reproducing it during the sample collection.
Open Activity Monitor from the /Applications/Utilities folder.
Select Path Finder in the process list. To help making a selection, type "Path Finder" in the Filter field.
Click the Sample Process button in the toolbar - this will open a new window entitled "Sample of Path Finder" and a sample of the process is collected.
Click Save and save the sample file.
Close (Command-W) the Sample window opened in step 2.
Here is a PF sample file when it was stuck on a path and clicking in the sidebar did nothing:
MrMuscle:downloads mnewman$ sample 1577 > pfsample.txt
Sampling process 1577 for 10 seconds with 1 millisecond of run time between samples
Sampling completed, processing symbols...
Sample analysis of process 1577 written to file /tmp/Path_Finder_2020-02-02_162921_sera.sample.txt