Have you looked at this document that Avalara has on this? The Resolution has a step process to set this up.

ACTION NEEDED: Colorado Retail Delivery Fee begins July 1, 2022 - Avalara Help Center

I have been successfully using it. The line item in Sage will stay at $0.00, it just updates the total sales tax amount on tab 4 with an extra $0.27. 

Did you setup misc item like /CORDF or is it a real item? I setup the OF in the Avatax tax maintenance so it lists in the tax detail but is zero.

I set up a miscellaneous charge not a real inventory item. You won't see it as a separate line in Tax Detail, it's just in the total sales tax amount.

I guess I might have something not setup correctly. What I thought was needed is misc item as a miscellaneous (not a charge). Order qty of 1 but leave the amount as 0.00 on the SO. When I add this /CORDF to the SO, the tax never changes.The /CORDF is mapped (with the /) in "What we Sell" in Avalara. 

For you is it properly calculating tax in SO entry? If I do an invoice, the $0.27 DOES get picked up.

DSD Business Systems has a great post that provides several options for implementing the Colorado Delivery Fee 

1. Miscellaneous Charge LIne
2. Use a new sales tax code ( I think this is Sage's suggestion )
3. Use AVATAX
4. Use DSD SO-1052 (Enhancement)

Link to the article - www.dsdinc.com/.../