Thank you for this! Tracked this down and locked in a $1,964 refund.
Some additional notes on this:
You can avoid this step by filling out Form MW506R, "Application for Tentative Refund of Withholding on 2020 Sales of Real Property by Nonresidents" at least 90 days after you close on the sale of your property.
MW506R can be found here:
https://www.marylandtaxes.gov/individual/income/forms/2020_Withholding_Forms.php
If you don't file MW506R by Dec 1 of the year in which you sold your property, you'll have to follow TerryA's directions above to receive your refund/excess withholding (like I did).
Cheers!
