Long Midi Notes Getting Cutoff

After upgrading from Cubase 8.0 to 8.5, long midi notes (for instance, whole note string melodies) are ending prematurely. It almost seems like I’m running out of usable midi notes. If I mute some midi tracks, the notes play normally. The only thing I have tried so far is unchecking “Activate ASIO-Guard”.

Cubase 8.5
Dual Xeon CPU
24 GB Mem
Win 7 x64
Steinberg MRX816
M-Audio Midi interface