Welcome back

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1. Currently, with the ongoing COVID-19 pandemic it looks like FLR (M) applications are taking approximately 5-6 months to process. Is this time frame correct?
I think they're generally taking around 3-4 months at the moment (normal processing time is 8 weeks), though it may be faster in some cases.
People who applied online in August and submitted biometrics using the IDV app in September were receiving their visas in December. However, I believe they were processing applications with biometrics submitted at appointments even faster than that, and all biometrics are done by appointment instead of the app anyway as they stopped using the app a couple of months ago.
2. My spouse has an unwell family member and there is a possibility that she may have to travel back home next month; however, my understanding is that this would not be possible while her application is being processed (without voiding the application itself) - is this correct?
That's correct.
3. Is there any indication as to when priority processing will resume? We were hoping to apply via ‘priority service’ or ‘super priority service’ to allow her to travel back to her home country next month (if required), but it looks like this will not be possible either.
There's only one priority service offered for FLR(M) applications:
The £800 24-hour Super Priority Service, which gets the visa decision made within 24 hours of the biometrics appointment, and then the BRP is mailed within 10 working days.
Unfortunately, though, it has been unavailable since March 2020 (when the UKVCAS centres closed) and we don't know when it will resume.