What are possible causes when MFG gives the wrong or no formula after Find by AutoMSMS is run?

In this case, the user runs Find by AutoMSMS on Q-TOF data, then performs Molecular Formula Generation (MFG) on the Compounds found.

MFG finds either the wrong formula, or no formula at all. It is possible that finding Compounds by Molecular Feature Extraction (MFE) and then MFG may find the right formula.

The cause is that the Acquisition settings are incorrect for what the user wants to achieve. For example, if the Isolation Width MS/MS is set to Narrow, then the Find by AutoMSMS would not find all of the isotopes. Missing these isotopes throws off MFG such that it would get an incorrect or no formula.
The solution is to change the Isolation Width to a wider value like Medium.