I would like to share an issue similar to what Tonyshred describes. In my case, it concerns programming the hot switch with the “EQ Compressor” algorithm.
On the software side, my H9 firmware is 5.9.1 and I am using the 4.03 version of the iOS “H9 Control” app to control the H9 over Bluetooth.
Using the iOS app, programming and switching the hot switch ON and OFF works fine. The issue arises after having uploaded the preset to the H9. When the hot switch is ON, the sound is much different from what it was using the iOS app : it gets high and shrill. Thus, I have reloaded the preset from the H9 into iOS. I observe that, when switching the hot switch ON and OFF, the various buttons controlled by the hot switch move but the Treble control. I suspect the information related to the Treble control is not stored on the H9 after uploading the preset. The sound suggests that the treble boost is maximum, while it is visibly set to -4.5 dB. As soon as I move it a little, all the highs disappear.
Any idea to avoid this issue ?