Just a suggestion
I also used to use the RME Multiface - but had similar issues to you.
My problem was that every time Microsoft updated Windows (which is at least every 2 weeks) - I would have to re-install the RME drivers.
Which as I remember was quite a tricky process.
Could you try using another sound card?
That was my solution to the problem.
I changed to the Steinberg 816csx when it came out - and have had only a few minor driver issues.
I also have used this live on many occasions - I have always found it completely reliable.
I haven’t missed the RME Multiface - and I know of at least one more person who has had the same issues too.
As you say - ‘when’ it’s working - it’s great!