Maybe it is something in your data? (inheritance of TF_XMLForm? inheritance of other classes used within? dangling pointer? ....)
Can you provide a "cut down" simple project, that we can open in our IDE and run, and that will have the crash?
I understand you want an lfm.
And even if you changed your mind, it might be helpful to first understand what went wrong. So following this up should stay on the table.
But I thought I might yet point you to an alternative, that may be of interest.
TRttiXMLConfig in unit Laz2_XMLCfg
This will write published properties to an xml file. (It is what the IDE uses for it's own config).