Hi, I've been trying to add flow button into the BPF as is described here:
https://flow.microsoft.com/en-us/blog/preview-instant-flow-steps-in-business-process-flows/
I've created new BPF called "Opportunity TestBPF".
My Flow is following 
In the BPF on the opportunity record I can see button for triggering the flow. 
but if i click on it nothing happen. Instead of button there is label "processing" but the flow wasn't triggered.
As you can see on the image below flow wasn't triggered. Not even once.
Can somebody tell me what I'm doing wrong? Thank you...