I'm using SkySafari 6 PRO (Mac version). Looks like 46P/Wirtanen data downloaded today refer to 7/7/2018 and this causes a slightly difference between actual and predicted position. Stellarium uses the same data taken from IAU Minor Planet Center and gives the correct position with respect to the images I'm taking these days.
These are the most recent data available from IAU. Note epoch (20181207)
0046P 2018 12 12.9282 1.055359 0.658704 356.3359 82.1590 11.7471 20181207 14.0 6.0 46P/Wirtanen MPEC 2018-W59
that are different from data available in Skysafari after an update. Orbit elements are still referred to 20180707.
Can you please check?