Orange 3 "Find Informative Projections" and target variables?
Slightly related with the question (issues with Find Informative Projections), I found this post trying to solve this issue: the tool Find Informative Projections was disabled and Orange did not provide any hint about why.

In the end the issue was on my side: I forgot to set any variable as Target when loading the data so it was useless to select it in the Scatter Plot points-colors section.

Double click on the File to load the data where you can choose if a variable is categorical or numerical, then double click on the variable I wanted to use as Target (that was marked as Feature) in order to select it as Target and the Find Informative Projections was enabled again.

PS: I have also noted that when making predictions, the file loaded should have all variables marked as Features. If you mark as before one of the variables as target, Orange shows a red circle with an exclamation mark on the Predictions widget, and a message: "Data does not have the same target as predictors" (even though it is). I guess that the target in the prediction file is automatically set by checking which info is missing in the file.