For posterity, the chain suck issue has been resolved. The chain rings were the issue. Upon closer inspection the small ring was more worn than I realized and had small mushroomed edges one side of the teeth which may have been holding up the release of the chain:



I sourced a new small chainring and the chain suck went away on the small ring. However, I was still getting a bit amount of chain suck on the big ring, too. I then went about hand filing the teeth judiciously to remove the slight beginning of a shark fin shape. A new big ring will be needed sooner or later, but for now all is working smoothly.