I've had similar problem with SAA flights posting to UA account on UA codeshares within SA and also Europe to SA. Once I submit the request online though seems to post within a day or two, but is troubling a request has to be made.

OT but I looked at the EQMs for SSA posting to United. Have they recently been reduced? Seems 70% on most economy fares and 100% for C. Seems flying LH Europe-SA is more lucrative for mileage plus...