Bugfix: changing date of instance of recurring appountment always gets undone at next synchronisation;
it is not possible to chamge the date of an instance of an ios or google calendar. The date gets changed on google calendar itself but reversed in the OneCalendar app and it sors also not gets changed in the iOs calandar app.
note: it does seem to work when it is the LAST instance of the recurring appointment.
this is a serious bug, makes me change app!