I'm assuming you're using the IAC bus to use MIDI over ethernet with less latency.
Is it a latency issue? I think there's been a locked-in buffer increase in the last update. –At least that's how it's playing out in Pro Tools 2019.12 and the UAD Apollo 8 via Thunderbolt on a top-spec 2018 Mac Mini. The slave computer is via Gb ethernet with an i9 9900KS with 64GB RAM and 2x PCIe Samsung 970's.
I rolled back to VEP v7.0.926 because it would not respect my latency buffer settings:
My Pro Tools buffer is set to 128 on the Mini, yielding 3.36 ms at 24/44.1 KHz is useful to me.
The latest update locks me in at 14.46 ms @ 24/44.1 KHz and 14.46 ms @ 24/96 KHz, even if I go into each VSL app and reset the buffer to 128. I've also disabled all VEP7 plugins except for the instruments. I don't even use the built-in reverb in the VI's and the Syncron Player apps.
If this is your issue too, back up your templates, clear all of those preferences, uninstall all traces of VSL apps and try rolling back. It was a PITA, but now I can work as I did before.