Excel 2011 for Mac VBA and El Capitan

Excel 2011 for Mac VBA El Capitan

We've had macros running fine in Excel 2011 on a 21.5" iMac running Yosemite 10.10.5.

Having 'upgraded' to a iMac (Retina 5K, 27-inch, Late 2015) running El Capitan 10.11.3, we now find macros failing with Date functions misbehaving. And that's just the first VBA bug we've come across.

Microsoft won't talk about any technical issues unless I pay them $500 and then they may well say they have't had this problem reported to them as their software hasn't changed and I should therefore go to Apple - whereas Apple say that they've had no issuers reported and so I should go to Microsoft!!!

In the immediate window:
Yosemite - ?Date results in 31/05/2016
El Capitan - ?Date results in 31/05/ (no year!)

Does anyone have experience of this problem?

Would upgrading to Excel 2016 make any difference?

Is there a workaround?

. . . or should I just downgrade back to Yosemite?

Many thanks,

Jon