OK, so this is a little weird. I have a mono WAV file. If I drag this into a new project it creates a mono track as expected and playing the project plays the audio. However, if I add an stereo effect in the insert slot it seems to be ignored. I tried it with the StereoEcho plugin and there was no audible echo of any sort. BUT … if I create a mono audio track using “Add Audio Track” then drag the same file onto the track everything works. I can add the same echo VST and it works perfectly. This seems to happen with all effects, I’ve tried with UAD, Softube, Waves etc including the stock Steinberg ones.
There are no differences in the settings or displays for the two tracks. Both are showing as mono, both play correctly but the one where I created the mono track by just dropping the file doesn’t use the effect. I thought at first it might be down to stereo effects just not working on a mono track, but they do work when added to a mono track that’s created using “Add Audio Track”.