No response to ProtoOASubscribeLiveTrendbarReq

Hi, 

For context I'm working with OpenAPI.Net and using protobuf.

I'm experiencing an unusual behavior when working with trendbar subscription requests. 

When sending a ProtoOASubscribeLiveTrendbarReq request, I do not receive a response (ProtoOASubscribeLiveTrendbarRes). The server seems to acknowledge the request though because after sending the request, the trendbars are sent in spotsevent. The same issue occurs with ProtoOAUnsubscribeLiveTrendbarReq. 

In contrast, ProtoOASubscribeSpotsReq works normally and returns a response with ProtoOASubscribeSpotsRes. 

Is this an intended behavior in the API? Am I potentially missing something in my implementation? 

observable.OfType<ProtoOASubscribeLiveTrendbarRes>().Subscribe(LiveTrendbarsResponse); //LiveTrendbarsResponse doesn't get called after subscribing to live trendbars
observable.OfType<ProtoOAUnsubscribeLiveTrendbarRes>().Subscribe(UnsubLiveTrendbarsResponse); //UnsubLiveTrendbarsResponse doesn't get called after unsubscribing from live trendbars

observable.OfType<ProtoOASubscribeSpotsRes>().Subscribe(SpotEventResponse); //SpotEventResponse gets called after subscribing to spots
observable.OfType<ProtoOAUnsubscribeSpotsRes>().Subscribe(UnsubSpotsResponse); //UnsubSpotsResponse gets called after unsubscribing from spots

I'd appreciate any insights or guidance. Thanks in advance!