Simple(?) issue with using =DATE and =SUM

[JackOfBlades]

For work, I'm creating a schedule that has automatically updating dates. In the first relevant date hex I've inputted '=DATE(year;month;day), which by itself works fine. Now, this afternoon I saved the excel file with the other cells referring to one another (and to the original) with the formula =SUM(original or last cell location)+1 and that worked fine. I had every cell fill itself with f.e. April 11th, April 12th, April 13th, etc. Incl. when it got to April 30th, after which it resorted to May 1st nicely, but now, a few hours later, it has suddenly replaced my nice little system with a cut-off at the last day of whatever month it is on. Going from April 30th to ############# instead.

Any idea on how to fix this? Odd that it happened without me changing anything (as far as I'm aware.)

 

[JackOfBlades]

Alright, well... Apparently it had something to do with the actual cell sizes. When I used 'automatically set cell width' or whatever it is specifically called, it fixed the issue and resorted back to using the correct dates, wonderful. Leaving this up for anyone who runs into a similar issue. The problem occurred because 'August' is a significantly shorter name than 'September'...