excel skips to another workbook for no apparent reason

Well I appreciate your comment. Although it was a little presumptuous to think that this was incorrect, it merely did not tell the entire story. This did indeed stop the issue from happening to me. But why it did turned out to be a secondary behavior issue. I was able to force the issue to occur about 50% of the time in a specific scenario after a couple of days of no issues. You were correct that the timing has to do with typing in the formula bar. I do a lot of typing in formula bars and that is when the issue occurs. I was able to duplicate the issue whenever the cursor was in the center of a formula and I clicked enter (about half the time). Since I was using the enter to navigate to the next cell I would do this often to be done typing and to be at the next cell. So by using different methods to confirm the formula and by keeping the cursor at the end of the equation I have not had the problem duplicate. I cannot say for sure if there are other ways to make this occur, but it was the first time that I was able to repeat an action and see the problem after the action. 100%, nope, but about half the time. I was unable to get it to occur when the cursor was at the end of the formula.

Been a problem for years and we have only seen tumble weeds. Beyond poor. Microsoft would rather release another useless new feature than fix their own product.

I have the same issue. It doesn't jump to another cell in the same workbook or worksheet. I think that's a different problem. Mine jumps to a different .xls file that is open and minimized, it might have links, it might not. If I have only one workbook file open, I don't see it happen. I can be quite fast in Excel when I'm working but when that "skip" happens, it slows me down and it's annoying. It takes my thought away from what I'm doing. So if anyone has any real fixes, I'd love to hear about it.

This solution seems to have resolved the problem for me. I have not had a recurrence of this issue since running each instance of Excel in a separate process. 

So, this is a very helpful tip. Additionally, I deleted the default Excel shortcut in my task bar and replaced with the shortcut that contains the /x switch.

I think, though, that it takes away from the point of multi-document-interface in that Excel has a tougher time communicating with itself on cut-and-paste options (that I've noticed). So, MS needs to resolve the issue. It can be a VERY critical issue for those users and companies that depend on Excel (and what company doesn't, at least to some extent).

Thank you JonathanKung

I have to agree.  I will be canceling my office 365 subscription next year.  If you don't like the product then quit paying for it is my stance.  Time to look at google sheets and see if that will do the job for me.  Using excel has me concerned I will corrupt my data.