I recently refinanced through Credible. Initially I did it with Loan Depot, the transaction was totally smooth all the way through signing.
Then the next day the Fed did an emergency rate cut, so I cancelled the loan with my 3 day rescission period. I re-refinanced through Credible again. This time with UWM (I had to use a different lender the 2nd time). The 2nd time through was a bit more of a headache. I suspect most of it was because we were in the middle of all of the COVID madness. This was mid March, so everyone was figuring out how to work at home, and the lender wanted to multiple checks with my employer to make sure I still had a job. The closing date got rescheduled a few different times, and I didn't get my final closing statement until hours before I was scheduled to sign which was frustrating, but it all worked out in the end. I was also assigned to a different team within Credible, so maybe they just weren't as good as the first one. At both closings they sent a notary to my house to sign all of the paperwork, which was convenient.
I did not have any issues with the rate changing once it was locked (either time), but the rate I was initially quoted on the website ended up being higher than what I ended up getting. Rates are constantly changing, but once you lock, I think you should be good.
TLDR: First experience was excellent, second experience had some hiccups but was fine.