OpenSM preventing sleep

I have 3 computers with Infiniband cards: 2 running Windows Server 2016 with a MHGS18-XTC single DDR port card and one running Windows 10 with a MHGH28-XTC dual DDR port. All card have the latest firmware and I’m using the last driver to support the Infinihost III cards, which is 2.1.2. The dual port was actually an HP branded one that I updated using stock Mellanox firmware (yes I used the correct firmware to update it).

The cards work fine, and speeds are good. However, whichever computer is running OpenSM as the subnet manager will not go to sleep, either after a set period of time, or when selecting sleep from the power menu. The display disconnects as well as USB devices, yet the fans and everything else in the case remain on. I’m 99.99% sure it’s OpenSM becuase it is the only change I’ve made recently and when I stop it in Task Manager and then sleep, the computer will sleep.

Is there any way to fix this, or am I going to be stuck manually stopping the service every time I want to sleep my computer?