We've got a handful of pledges that when we try to make a pledge payment on them, the pledges in question don't show up in the list of Existing Contributions. We have Automatic notification of Open Pledges set in preferences and for all the pledges in question, it's the only open pledge on the constituents, but it doesn't pop up. We can see the pledge on the contributions tab of the constituent record. We checked that the campaigns and funds and sources are all active. The batches the pledges were created in are posted. Why else might open pledges not show up?
Turns out a while ago we had an issue with some batch types not having business units and fixed that then but didn't realize the trickle effect to the pledges. Fixing the bu on the contributions seems to have done the trick.