Transition out of simple sync on Rev 7 (is this a bug?)

I'm trying to learn sync (sacrilege I know), on the Rev 7 with Serato Pro. I don't understand you transition out of simple sync smoothly. What I observe is the following:

1) Track A is playing to the audience at say 100 BPM

2) I load track Track B (orig. 105 BPM). I hit sync on this deck, and the temp snaps to 100 BPM. 

3) I complete my blend from Track A to Track B. 

I now want to transition Track B to 105 BPM. If I now turn off sync on this track, (Shift + sync) then this track seems to immediately jump to 105. This transition is abrupt, and sounds horrible!

Am I doing something wrong? I've also tried moving the pitch slider to 105, then turning off sync, and this just jumps to whatever is correct for the pitch slider. I've tried using Reset as an intermediary. but that doesn't seem to work either. 

Is this a Pioneer issue or a Serato issue? Feature or bug?

Thanks!