Compatibility to BB86 I have a second hand frame circa 2014 that measures about 74mm across at BB.

I'm fitting an Ultegra crankset.

Shimano states I need a BB94-41 for a shell width of 86mm ?????

Am I reading this wrong? how can a BB86 fit in a frame width of 74mm.

Im confused
You have the 73mm version of either BB30 or PF30. Running a Shimano road crank will be physically impossible because the spindle isn't long enough.