Rollup Doesn't Work Consistently on Delete

[Boyd-Campbell]

Some wonky behavior. No clue what's up. I cannot pin it down to a science.

1. Add a Product line item on Quote
2. Add a second, then third
3. Rollup calculation works during each add
4. Delete one of the line items & the rollup fails to update
5. Delete another and it updates
6. Delete the final line item and it doesn't update

I'm afraid this is relatively unusable like this. Help?

Love your stuff man. I really, really hope this project isn't dead. I don't have time to branch & remedy myself. Thank you!

[hydr]

The reason here is that workflows are triggered before the delete is actually executed, in the "pre operation" step. I don't think it's possible to achieve a consistent behavior when items get deleted with workflows.
Building a custom plugin works as an alternative, there you can trigger on "post operation delete".