Effects pasting onto source instead of timeline clips

I've been using the same colour correction workflow for years without issue. I switch to a colour correction layout, turn on selection follows playhead, then use up/down to quickly advance through the timeline to colour correct. Typically I copy Lumetri from one clip, advance to the next, paste Lumetri, make any minor adjustments required, then advance to the next and repeat.

Lately, when the Lumetri color panel is active, copied effects paste onto the source clips, instead of the selected timeline clips. The only way to avoid it is by clicking into either the effects controls or timeline panel before pasting. I edit hundreds of clips every day, it's a very annoying extra step to have to take now and seems very clearly to be a bug. The bug also occurs when the program monitor panel is active, and happens with any copy-pasted effect, not just lumetri. It also occurs in any window layout, not just colour correction.

See the attached screenshots. First screenshot before pasting an exaggerated lumetri effect shows that lumetri color is the active panel, it shows the timeline clip is selected - not the source - and the clip is clearly highlighted in the timeline itself. Effects controls also confirms I'm working on the timeline and not source footage.

Second screenshot is after pasting the effect. You can see it's clearly been applied in the program monitor, but the effect is missing from the timeline clip. Third screenshot confirms it's on the source.

Premiere version 25.4.1 build 3

Intel Core i7-14700KF (3.40 GHz)
RAM 128 GB

Gigabyte RTX 5070 Ti 16 GB

Windows 11 Pro
Version 24H2
OS build 26100.6584
Experience Windows Feature Experience Pack 1000.26100.234.0