Bad tiles added to tilemap

Really digging the tile features but am experiencing a strange behavior.

While working on a Tile Map project, whenever I toggle sync mode, the tile my mouse cursor is hovering over gets added to my tilemap as a unique tile.

(in this screenshot I’m using a purple 1px brush)

Probably a rare problem for users because you have to set a keyboard shortcut to toggle sync mode, otherwise you toggle sync by clicking the button in the top bar, therefore your cursor isn’t hovering a tile. But I toggle sync constantly so a keyboard shortcut saves me a lot of time and sanity.

If I repeatedly toggle sync mode as I move my cursor around randomly, numerous new tiles get added:

Running an Optimize does remove the bad tiles, since those tiles don’t actually exist in the project.

I believe this is related to how Pro Motion treats the brush on the cursor as part of the layer contents, as evidenced by how your brush cursor is represented in the Preview window too, in real-time (which is awesome! I use it to quickly find where I’m currently pixeling by moving my cursor around in a circle as I glance at the Preview window when checking how my image is coming along).
If any sort of update was ever made to how PM detects new tiles by ignoring the brush cursor I would hate for the Preview window to no longer include your brush cursor.

Thanks! Did not notice that because the default key shortcut used Ctrl key which hides the brush and activates the temporary pipette.
You are completely right with you assumption. In the current public version the brush is rendered directly into the canvas and not as kind of overlay. The rendering engine has been re-coded for 7.3 (spring release, hopefully) to also better support overlay elements in common, so this problem is solved there automatically along with several other benefits that I need for new tooling (e.g. floating selection).

I also fixed this bug for the upcoming maintenance release.

Sweet! Thanks for letting me know.