Problem with hyperlinks to Excel workbooks on OneDrive

[rjxb]

I have scores of Excel workbooks, incorporating hundreds of hyperlinks to each other and to other documents. All these Excel workbooks and other documents which they link to are saved in my local OneDrive folder for data safety reasons. Until recently, I was using Excel 2007 and the links all worked perfectly. However, now that MS are no longer providing support for Office 2007 I "upgraded" to Office 365 (ie, Excel 2016) and have a couple of problems: one fairly minor, but the other not so.


The minor problem is that activation of ANY hyperlink now ALWAYS generates the warning 'Microsoft Office has identified a potential security concern. This location may be unsafe.' This happens with all the OneDrive files, even though OneDrive is a Trusted Location, and also with files saved to my desktop (also a Trusted Location), whether they are linking to another file on the desktop or to a file in the OneDrive folder. I know I can switch this message off permanently by fiddling in the registry, but this defeats the object - I want to be warned if I am about to jump to a file which is not in a Trusted Location, but not every time I jump to one of my own workbooks.
The more serious problem is that if I activate a hyperlink to an Excel workbook in the OneDrive folder, it will work fine as long as the file is not open. Once the file is open (which activating the hyperlink will do, of course) any further activation of hyperlinks to that workbook will simply generate the error message 'Cannot open the specified file'. This happens regardless of whether the source workbook containing the hyperlink is in the OneDrive folder or saved locally, but does NOT happen if the target workbook is saved locally (desktop, root, etc.). In that case, the hyperlink will just jump to the required location even if the file is already open - as it should. What this means is that, in order to have working hyperlinks, I have to close any OneDrive workbook once it has been accessed. I do not want to do this, should not have to, and did not have to with Excel 2007. Nor do I want to save all these files locally, since my whole rationale for using OneDrive is cloud backup.
This problem relates specifically to target Excel workbooks on OneDrive. Word doesn't care if a target file on OneDrive is open or not, so a hyperlink in any Word document just jumps to the required Word document on OneDrive; and a hyperlink in an Excel workbook to a different type of file, pdf for instance, works fine (in both cases after having warned that there is a potential security concern, of course).
I do not understand why something which worked perfectly well in Office 2007 does not appear to work in Office 365. There may be a simple setting which I am overlooking (it has happened before!) and, if so, I'd be grateful for a nudge in the right direction. If not, does anyone have any bright ideas?