Media Encoder reading Source timecode rather than setStartTime

Hey Folks

This is probably a niche problem, but I've been having issues with the metadata & timecode effect, where the burnin in premiere wouldn't match an export via media encoder.

And I think I've narrowed the issue down.

Let's say I have a clip with a start timecode of 00:00:20:00
I import, then set the start timecode to 00:00:25:00 using

item.setStartTime(startTime);

where item is

app.project.rootItem.children[numItems];

Adding the metadata effect, in premiere it reads 00:00:25:00. If I export directly from the timeline, the burnin on the resulting mov reads 00:00:25:00. But if I send it to Media Encoder, the burnin will read 00:00:20:00, both in the preview window and in the resulting mov.

My question is, is this expected behaviour? Is there a way to burn in the modified TC when using ME?

I've tested this on both 2024 and 2025.

Thanks!