Hi Bigben932~
I don't have an answer for your issue but did find some materials that could help. Apologies if you've already dug into these but thought I'd pass on.
K14754: BIG-IP support for the WebSocket protocol:
https://support.f5.com/csp/article/K14754
K14814: The BIG-IP system may drop WebSocket traffic:
https://support.f5.com/csp/article/K14814
K15357: WebSocket connections to virtual servers may fail when using OneConnect:
https://support.f5.com/csp/article/K15357
and one pertaining to v12:
K04597703: Overview of the Local Traffic Policies feature (12.1.0 and later):
https://support.f5.com/csp/article/K04597703
hope those get you in the right direction.
ps