Worked yesterday, not today - Siri reminders adding to Microsoft ToDo

[matt8268]

Just started using Microsoft To-Do. Two days ago I set up and tested using "Hey Siri, remind me to comb my hair", and it successfully added to my default "Tasks" list in Microsoft To-Do. Then yesterday, doing the same process doesn't add them to Microsoft To-Do. They do get added, though - I can see they were added in the Apple Reminders App under "Tasks, Outlook". But they don't show in Microsoft To-Do. I recently upgraded to ios 12.4, but can't remember if that was done in between this working and not working. 

I found another post with a user experiencing this exact issue, but there were no replies. Has anyone else experienced this issue? Is it a known bug, or are there known workarounds/fixes? Can someone confirm Siri reminders are showing in app in ios 12.4, so I know it's just me. 

Thanks,
Matt.

[#2]

and now today 8/3 the reminders I put into ios via Siri days ago just showed up in Microsoft To-Do, and I added a new reminder just now and it showed up immediately. so whatever was causing this issue is now fixed, but I have no idea what fixed it (I didn't do anything, and Microsoft To-Do app wasn't upgraded).