Latency on master but not on input

Hello! I recently switched from Tracktion Waveform 10 to Cubase 11 (a fantastic switch by the way, I love it), and have learnt my way around it pretty well. I have had no problems with it up until now, when a strange latency has suddenly appeared in one of my projects:
I can see on the faders in the MixConsole that the mono in (for a guitar) is completely latency-free and responds directly, just like it’s supposed to. But the Stereo Out outputs the audio with a significant latency of half a second or so. The audio chain is Mono In > Audio track > Group track > Output. The only one of these that has inserts is the audio track, and the latency remains even after disabling all those. I have no Master track inserts and my Control Room is disabled. If I start a new project the problem disappears.
Does anyone have any idea what the problem could be?
Thanks (:

Update: I solved it myself! It seems that a compressor insert on the audio track was to blame for the latency, even when disabled. Which is interesting though, since that means that parts of the insert VST must still have been active after I disabled it, or something like that. Is there an explanation to what happened here, just to prevent it happening in the future?

You can Bypass an Insert (which does leave it still active, just its input is muted) or turn it completely off. If you hover over the Bypass button it will tell you how to do both (Click = Bypass, Alt+Click = Disable). If the plug-in GUI is open there are individual dedicated buttons for Bypass & Disable.

I understand, that makes sense. Thank you!