What seems to be happening is a bad calculation of the time for the stacks that are done after the duration of time of the buff you use.
If you notice, for those who have enough troops on queue to be affected, the top stacks all are taking the right time they should for example for 25k 23 minutes and some second but if you scrol down to the last 2 stacks and you check the time a stack takes it's almost 48m or more it's very wierd. BUT once the buff is done or removed time gets back to normal, so in practical terms the bug is "just" cosmetic because the stacks under the influence of the buff are being made at th speed they should, and once the buff ends the times get back to what they are supposed to be. So it's just annoying but we seem to not be losing time at al.