To add to Larry's suggestions:

I just tested a couple of things
1. Amplitube does not work when it is plain Midi, i.e. there is no DXi or VSTi selected in the first place.
2. If I select Coyote WT or SampleTank 2 as a PlugIn in the first slot and then select Amplitube in the second slot it works as intended.


Desktop; i7-2600k, 8 GB mem., Win 10 Pro, BIAB 2017; RB 2017 - latest build
Laptop: i5-2410M, 4 GB mem, Win 10 Pro, BIAB 2017; RB 2017 - latest build