It would appear that the update to fix all day events may have worked in timezones east of GMT/UTC but it made the issue worse in timezones west of that line.
All of my events are in a google calendar, were made on my phone or computer by me, appear correctly on my calendar app(stock Google calendar app) and computer, and are all day events. However, in your app, they disappear 14 hours early. Prior to the update they would disapear 7 hours early, equal to my offset. My timezone is currently GMT-7, so I guessed that the 14 was related to the timezone. I have since found a woman on here who is in GMT-5 and her all day events dissapear 10 hours early, again double her offset. So my guess is your fix worked for the timezones ahead of GMT but does not take into account the - in the offsets for those of us behind GMT. All it needs to do is reverse the addition or subtraction you did in the first fix if the local timezone is east of, meaning has a negative offset from GMT. Just grab the + or - in the offset when grabbing the offset to do the math calculation and it should work.
If a donation would speed this fix, I'd happily contribute $10 since the code is there and it really should be a fast fix.