Mouse click requires double click to enter input if "Set Input Mode Game Only" used
Regression (no) issue (does) occur in 4.12.5
Notes The first box selected will light up correctly the first time it is pressed following the repro steps. All other boxes require a double click to light up.
The first box lights up. The second box requires multiple clicks to light up.
Both boxes light up after a single click with LMB.
Head over to the existingAnswerHub thread and let us know what's up.