This is the first time my refund has ever been held up. Electronically filed immediately after the ACA update was fixed in the tax software, it was processing and the converted to "still processing" mode which I assume means something triggered a further look. Been checking the mail box wondering if they needed something. Not sure if there is a set amount of time one should wait before calling given how backlogged they are.
I also filed right after ACA update in Turbo tax. Just this morning, 'check my refund' reports refund approved, and should be deposited this week. I had strange results this year via Turbo tax, $1 penalty? Due to estimated taxes late I guess, though think I did that right but honestly well worth $1 not to have to fill in form 2210. And the ACA no clawback of tax credit seemed like it might trigger some kind of extra IRS time. I hope you have some positive info on your refund status.