Silly me, I didn’t catch the error way at the bottom. Sorry about that. But to fix you need to install the stashapp-tools dependency. You can do this from the install task for the SIT plugin. I’m not at my desk ATM but I think it’s under the Tasks section in task settings.. all the way at the bottom you should see Stash Interactive Tools
It should look similar to this (this is an old screenshot before the install task was added but still same look)
Click on the install button and hopefully that error is no longer there and plugin works correctly when viewing a scene.