"Commencement of operations" in Texas

I bought the property already leased. Like 99% of all leases I have seen, the lease does not specifically define what constitutes operations which will extend the primary term. That would require a special clause and this lease does not have one. Therefore, it’s certainly not black and white. Hoping that someone knows Texas law.

Recently, the Lessee offered a new lease, with lease bonus, but now says Oops, we made a mistake, you are in a unit. But to my knowledge, all they did was get the survey plat and a drilling permit. There was no drilling rig on site at the end of the primary term.