1. Have an assembler with some recipe chosen and shift right click it to copy.
2. Have one inserter of any kind in your inventory
3. Take this inserter in hand (or "pick" it with Q) and place a ghost of it with shift left click
Expected result
The ghost of inserter is just placed.
Actual result
Not only inserter is placed, but also the recipe is pasted to this inserter (setting the filters) immediately after ghost-placement (because hand becomes empty and shift-click pastes the recipe, despite that mouse button has not been released). You can verify this by issuing "Undo" command (Ctrl+Z): the recipe will be removed from inserter.
Tested it on 2.0.20, just the space-age, elevated-rails and quality mods. Same thing happens - if you have only one inserter in your inventory, shift-click placing it also pastes the recipe copied from an assembler.
Thanks for reporting, I had the same issue, but only occasionally and couldn't reproduce it. Glad you figured it out, and thanks to Rseding91 for fixing!