Cannot select a line on the dynamic lighting layer

I have all the walls and doors on my map marked with a thin line on the dynamic lighting layer. The walls are a different colour than the doors, so I could go back and move the door lines when my players opened them. However I'm now finding that I cannot select certain lines. For some reason all the vertical lines are difficult to select or impossible. The horizontal lines don't seem to be giving me any issues at all, which strikes me as very bizarre.

Hi Joseph, thank you for the report. The Dev Team is aware of this issue and, as a workaround , recommends using a thicker line weight for your drawings until this issue can be fixed.

Cheers, using a non-thin line does help. What a peculiar bug.