Hi,
As far as I know there is no limit. I am not sure why you had to split it into 2 files. Were you using FDM mapper for creating the rules? If so, was it in the new style or old style of the mapper?
Considering the number of tabs in your case, I would recommend you to activate the "Old Style mapper" from the FDM GUI and re-try. It would be easier to handle as well. Please see the screenshot below to achieve this.
Let me know if this helps. If not, please raise a case with support and we will be happy to assist.
Regards,
Aditi
Sr. Support Engineer