Issue with BDB S-IVB and APS, and possible further issue with vessels that are too heavy.

[PhotonSP]

Using the BDB S-IVB and APS, it seems as if the APS does not provide the amount of thrust needed for ullage to work with Engine Ignitor, my best guess is that the S-IVB with the LM and CSM is too heavy by Engine Ignitor's standards, and thus does not see the APS as providing enough thrust for the engine to get in a stable configuration, as when the S-IVB gets lighter in terms of weight, or when the SM RCS is used, its perfectly fine and can reach a stable configuration easily. Such a restriction where the method of ullage doesn't provide enough thrust compared to the weight of the vehicle doesn't make sense to have implemented, as in theory no matter the weight of the vessel, as long as thrust is provided by ullage, it should still be able to settle the tanks.

Playing on KSP version 1.12.5, BDB mod and JSNQ planet mod.