Outlook limits the size of files you can send. There are a few ways to work around this size limit, including using a file sharing service or compressing the file. You’ll receive an error message if you attempt to attach files larger than the maximum size limit. Does not seem there is a workaround other than that mentioned, and what you did with installing different versions, but it seems there is a 20MB limit at this point. I was able to check my Outlook 2016 on my Windows laptop, and got this from Help. I suspect that Microsoft should be able to answer that question, unless you can see information about what the incremental updates to your Office 2016 would have done to adjust Outlook. It may also be something that you can adjust if you check with them, since all it seems is that you removed an update to Office that made the change. That is why I referred you to Microsoft to see if it was a setting in Outlook.
