I’m switching over from MainStage because of errors loading patches where instruments sometimes load a patch from another song. This is a disaster for live playing. I have spent months recreating over 80 songs with mostly Arturia VSTs. Here is my issue: Three times now it has played three different instruments in the wrong keys. The global transpose is still zero. The transpose inside the Omni Midi block is still zero. The keyboard inside the VST shows the notes I’m playing but it plays the instrument in a different key. Meaning: if I play a C the keyboard in the VST plays the same C I’m playing but the sound was a Bb. These seem to be random instances as it is just one instrument out of dozens I have loaded. Once it was the Piano V transposed up a whole step. Once it was a Vox Continental organ transposed down a whole step and one time it transposed my Oberheim OBX. Two times this happened while performing. I restarted GP and it went back to the original key. The piano went up a whole step while I was playing at home so I was able to investigate the transpose functions and they were all set to zero. One cusious thing: the Piano does not have an internal transpose feature so I don’t know how it could sound a D note when I play a C.
I have a midi monitor that shows the correct notes I’m playing even though the VST plays a different note.
Edit as this thread has been cleaned up: the original suggestion was to delete all existing CC mappings within the plugin itself (beseides the needed ones)
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Other approach: place a restrictive MIDI Filter in front of the Arturia plugins letting only pass Note On/Off, ModWheel, Sustain
I had this in the past, too 
Sounds like something is sending pitchbend messages to those plugins.
You can just block those events from the MIDI In blocks connected directly to the plugins - you don’t need another MIDI filter. That said, the OP should really figure out from where pitchbend messages are being sent.
Absolutely! Some more considerations about better using the additional filter:
- especially Arturia plugins react to a lot of CC’s which not can be filtered directly in the MIDI in block
- I had some plugins in the past which also reset their internal MIDI mapping after an update
- you can easily replace plugins without thinking about side effects because of receiving all kind off different CCs
- edit: and of course you may already have or need a filter to “mute/unmute” or bypass layer sounds, splits etc. within your rackspace
BTW: IIRC the Arturia Piano V2 had a master tuning control which was reacting an internal CC mapping which only could bve removed inside the plugin, or be filtered
Can’t you just unlearn them? And then use host automation via widgets?
That’s just another reason to NOT use MIDI Learn in a plugin
That’s what I tried to say in the following point: Unlearnt controls could be reset with an update, and so you would have to unlearn them again…
I installed a midi filter block on all the instruments. I like the midi filter block because it has more options. For instance, I can unblock the midi CC that go to the drawbars of my Hammond while still blocking dozens of others. I have a lot to work with now. Someone suggested that my instruments are reacting to a pitch bend command. That makes sense and I can block it on my piano and, perhaps most of the instruments but there are some that I need the pitch bend for. I’ll let you all know how it goes. Thank you for all the information that all of you are sharing.
I use Arturia VST almost exclusively and do not have this problem. I did have things randomly change though. Without doubt it will be random messages getting to the plugins. A quick way of checking is look at the patch name in the plugin GUI, it will show an asterisk next to the patch name is anything has changed.
As mentioned above, only use widgets to control your VST and connect the external controls to the widget via rig manager. It will be rock solid and can easily handle hardware changes.
You should check this by watching to see if PB messages are being generated. However, it’s possible that other CC messages are responsible for transpose - you’d have to look at the plugins, see what messages are tied to Transpose (for example) and make sure you’re not sending those messages by mistake.