Not this crap again.
Since you didn’t list any specifics I will only give you a thought…
Maybe there is a reverb turned on in your audio interface (AI). Maybe?
You might hear it if your AI has some kind of direct monitoring activated along with the reverb.
Regards 
The reverb is only in the headphones (I’m using the Phones 1 output of the UR44). Nothing is sent the the FX Bus. Reverb isn’t recorded either.
Well at least now you have listed the UR44…
The UR44 has a feature named “Latency Free Monitoring with FX”. If that was activated it would sound and act just as you describe. I don’t have a UR44 so I don’t know exactly how it works on that unit but my Presonus audio interface has a similar feature. It is activated when in the Presonus universal control center (not Cubase). That similar function is available in the UR44. You should review the UR44 manual as I believe it is controlled in Cubase as the UR44 and Cubase are somewhat integrated.
Regards
It appears to be a malfunction of some kind. Today the problem was gone as mysterious as it came. The thing is though - these random issues just kill a day’s work.
Open DSP app and set send to zero. problem solved