I am not sure you can go backwards with the software. Also you would miss other updates. As said by others, it could be different functionality between a hybrid and an all electric, so difficult to comment.
The software and app we refer to is designed for a full electric. This software, as with pretty much all EV is based on setting departure times and also the preferred (off peak ) charging times. From my experience it functions perfectly every time. Because it is such a small battery
, a 7,8KWH charger and I rarely start from ‘Empty’ the departure time is almost irrelevant. Based on my data the charging starts at the same time 1145pm and finishes around 2 to 3 in the morning. So the calculation is based on when to stop charging. So the fact I have a departure time set for 730 am for weekdays (normal departure time for my wife when she steals😉 my car) and 715am for weekends (someone needs to go and get the croissants🤨 ) has no relevance unless I was using the 13A granny charger).
For the other EV departure time is critical because the VW works backwards from departure time, preferred hours, and current SoC, the max charge rate possible, to determine when to start charging.
it is certain PHEV have a different method of calculation because the battery capacity is usually so much smaller.
i suspect you have another problem, but certainly you should not need a smart charger. Also the advice we got from our installer, is it is better in his experience, in France, not to have a smart charger because they tend to go wrong. His ‘call outs’ are usually to reboot a smart charger. However I cannot comment on how good the smart chargers are in the UK.