Copy and Paste Issue with a Column

So I have a date and time column of data and I am attempting to sort it by using =MID() commands. It has previously worked wonderfully but on this data set there is something different causing an error. When the cells are formatted, they show the correct date and time format that I am attempting to pull out information with using MID, but then the resultant pulled data is garbage. I couldnt figure out why this was happening and then I copied and pasted the original data into a new column. This revealed something odd showing that the data pastes as various numerical values around 42,000 or so. There is a pattern but I have no idea what it is. WHAT ARE THESE NUMBERS and why cant I simply copy and paste exactly what the cells have in column E in my "non working" picture attachment.

Thanks for your time.