The timer glitched on me too. I checked the bugs forum and didn't see anything about this....is it under investigation?
My secret thingamabob finished construction overnight so this morning I clicked on it for the first time. It said I had 17+ hrs to finish. Now half an hour later it says I have 5+ hours to finish. Not good!!
Seems right now that this will be a feature similar to the train in FS...something I routinely ignore. Haven't done one of those for at least 6 months. Always ask for something impossible and the reward isn't worth all the work.