Interesting chart put out by the TAS office showing the possible paths a return will take as it is "processed" ... so you can see that even when the "audit" docs are sent the return still has to go thru more hoops before a refund is issued. How long certain stages take to pass thru is totally dependent on the # of humans available to do the job and as we all know the IRS is way behind due to the covid shut down earlier this year ... so I can see where many places could have a large backlog of returns.
This chart also shows how returns with refunds and with balance dues are handled in separate "lines" which makes so much sense that balance due returns have been delayed in processing this year as they focus all the personnel available to getting out the refunds first.
Also consider that the same employees were redirected to putting out stimulus checks this year which means some other processes were either completely closed or severely understaffed.
https://taxpayeradvocate.irs.gov/Media/Default/Documents/2020-JRC/TAS_Roadmap_32x32.pdf
