What causes it? It’s built that way from the factory.

The wet output level is boosted no matter what the input level. The wet output level is never unity with the input.

The input output level switch are set to “line level”…

But in this instance our input level is 3V PP (+12) it does the same no matter what input level is used. I’ve tried all different input levels.

And, we tried (my friend’s) a second time factor unit (with updates installed), and it does the very same thing. So this is not a defect in the unit.

We are looking at these levels on an oscilloscope, there’s no mistake here. It’s built that way.

I find it very hard to believe that this never occurred to anybody: it’s obvious to anybody who measures it.

The level of the wet output is more than 2X input level, not unity.

If you want to make this compatible with an effects loop, the wet needs to be unity, not boosted.

You need to make an update for this pedal, that fixes the wet level problem. It’s a DSP; if you have the software you can do it.