@emmanuelbuccheri Loading a sample map always stops the audio engine.

To cross fade load the sample maps into two samplers at the start and crossfade between them. Or load the samples into multiple groups in the same sampler and use the group xfade feature.

I have an old video that shows some techniques here: https://youtu.be/0cn1l8231n4

Bump again

I finally solved this mystery, so here is the answer for anyone else who has this problem.

My MIDI keyboard for some nonsensical reason outputs on multiple channels at once. This causes duplicate notes to be sent to HISE which causes the group counter to increase twice for each key press. So the solution is to filter the incoming MIDI channel in HISE preferences.

Bump bump