Hi Alec, looks like a typo got introduced in recurrence instance matching.
In line 1206 (or thereabouts) the YdHIS should be YmDHis
$recdate = $recdateobj->format('YmdHis');
A fix with this in will be up soon.
Also please note
1) that your ics file is very large, my local server was timing out when trying to refresh it remotely, I had to download it and refresh locally. As you continue to add and modify events, the file will grow and that situation will get worse. It is also not easy to delete old stuff from google calendar. (search it!)
2) you have bad/mismatched html in your event descriptions. An ics event description is not really supposed to contain html. My plugin will attempt to cope with it (although not the mismatching). Some calendar applications may show the raw html.
3)with a complex mix of modified recurring events and modified recurring instances, the risk of calendar applications not interpreting the instances in the same way is high. For example: one of your recurring rules had as many mods made to it as an recurrence instance had had. The rule might also have a mod later than the instance. For now if there is an instance, the plugin will assume that that is the latest – however I can see that it is possible if there are lots of mods being made to instances to get the whole thing in a confusing state. If you are ever confused you could create a test evet list showing the recurrence id, sequence to see which the plugin is showing:
like https://i.imgur.com/2W7qHPF.png
Bit technical, but raised some of the problems that might arise with various calendar applications if one has complex interrelating modifications. https://icalevents.com/4437-correct-handling-of-uid-recurrence-id-sequence/