I made the same call last month with the same result. In speaking with another practitioner, he told me that since the election is not actually made until your file the 2021 return (in 2022), there is no liability at  year-end 2021. Kind of makes sense. The tax savings is deferred a year. 

This from a Journal of Accountancy Article dated December 20, 2021:

Crucially, a specified income tax payment is one the PTE "makes ... during a taxable year" in computing itstaxable income "for the taxable year in which the payment is made" (Notice 2020-75, Section 3.02(2)). Eventhough Sec. 164(a) provides that the SALT deduction is for the tax year in which taxes are "paid or accrued,"the more restrictive, literal application of the notice to taxes paid is the safer course, advocates say.
"The plain language of the notice strongly suggests that a PTE tax must be 'paid,'" said Alexander Scott, J.D.,LL.M., a senior manager with AICPA Tax Policy and Advocacy in Washington, D.C. "The prudent course doesappear to be to properly elect, if applicable, and pay by Dec. 31, 2021, depending on the state PTE regime, inorder to benefit from the SALT cap deduction in 2021."