Negative deduction issues in Payroll 2018

Working on a Payroll upgrade.  Client has cell phone reimbursements, with an annual limit, setup as a negative deduction.  This worked fine pre-2018, but 2018 gives a warning that the employee has already met the limit and you are taking MORE than the limit.

Strictly speaking, (288.80) IS larger than (540.00) (288.80 being the current YTD and 540.00 being the limit), but apparently the old versions was a little bit smarter.

We could change it to a non tax Earnings Code, but you can't put in limits on Earnings Codes, so we would lose that functionality.

Any ideas?

(Also, our flat 5% 401K is calculating differently in 2018, even if you added the cell phone into the gross... - still working on WTH with that one.)