Thanks LBH!
You're right, sync works but the parameter readout doesn't.
It's like
1/16 ~ 310
1/8 ~ 450
1/4 ~ 640
1/2 ~ 850
1/16D ~ 380
1/8D ~ 580
1/4D ~ 760
1/2D ~ 880
I hope Arturia will fix this.
And, while they're on it, use the way sync delay works in the 'newer' synths, with Time/Sync binary/Triplet/Dotted options (which is very convenient).