So, I was adding a few gym sessions (activity type as Other) in my calender to the future, and noticed that at least for me it seems using Chrome, that to get the desired time-of-day for the activity saved, the new activity needs to saved twice. So, when you add a new activity with all the desired information, the time-of-date seems to be left out, and you need to edit the activity to get the time-of-date added.
Thanks for getting in touch with the support team! We have an issue open for this and we’re actively working on the fix. Thanks for reporting, and for your patience!