This is a very minor cosmetic bug in the “Current Upgrades” window, but anyway:
After starting a Wave upgrade of which the max. duration is truncated to 2 days due to the current “Boost Your Defense!” event, the progress bar of all upgrades already in progress is also truncated to 2 days.
So for upgrades with time remaining in excess of 2 days, the progress bar remains empty until the remaining time is reduced to 2 days, after which the green portion appears to indicate the remaining fraction of two days, rather than of the entire upgrade period.
The indicated remaining time is correct and I assume that the upgrades will complete as normal, so there’s no real impact.
For upgrades started subsequent to the Wave upgrade, the progress bar displays correctly for the full upgrade duration.
I assume this is a platform independent bug, but I’m getting this on Windows phone 10 (Options menu says 3.9.1).