Seeing a LOT of (unresolved) questions around this. TT cannot efile because of form 7206. I called in to TT support and waited through the hold. Here's what MAY be happening.
Form 7206 has been "published" to TT. HOWEVER, it is still (apparently) in Draft form from the IRS. As such, TT (desktop for me) cannot efile because uncle sam still shows the instructions in Draft form. (Search "Draft Tax Forms" on irs.gov and that's where I still see form 7206 as "Draft").
SO, it appears the problem is, we are waiting the IRS to fully publish Form 7206, and THEN TT SHOULD be able to efile the form. However, no one was able to 100% confirm this. The advice I got was, "wait until after Feb. 15th when all Draft forms are SUPPOSED to be fully published..."
Not a great answer....but might be correct. Good luck.