I have been using Dropbox to open, edit, and store excel worksheets on multiple desktops and laptops for years without issue. I bought an iPad, and installed Office 365. Working through the Dropbox app., I am not able to edit any of the excel files, they are read only, and all of the templates have a spaceship icon. Working through excel, I can find Dropbox in ‘other storage’ and open and edit the selected worksheet. When I try to save it to the appropriate folder it won’t give me the option to save. So, summary; spaceship icon (correct extension), read only, and won’t save.
The extension is .xltx and it is 112 KB. This is only an issue with the ipad or iphone. It does not have an issue on any of my Window's based computers. I did read somewhere that saving it to a folder with more than 10,000 worksheets may be an issue, so that may explain why I can't save it to the desired folder, but even though I can save it to an empty folder, it is still read only.
I have Office 365 which works on the iPad. I can open Excel, select Dropbox storage, open and create a worksheet and save it on my iPad. It just won’t save to Dropbox in most of the folders, and the folders it will save to produces a read only copy in Dropbox.