Excel2016: Save as pdf in ProjectWise will not work

Hi,

We used to save Word or Excel documents as pdf by clicking F12 and choose (with or without Wizard) the Format PDF, to get the pdf directly in the same folder in PW as the original file.
This worked perfect in PW 8.11.11.590 with Office 2007.

Now we are with PW 8.11.11.590 and Office 365/2016 (and Office add-in 8.11.11.866). In Word saving as pdf still works, but in Excel it doesn't. 'Saving as' will give an error:

 followed by  , then 

As checking in is not possible, the document is freed in Organizer. But it still remains in the local PWWORK folder, as a .xps file (sorry for the blurry image):

So here is my question:

How can I save a .xlsx as .pdf directly in ProjectWise (without first saving it elsewhere then dragging it on PW)?

Note: same procedure without ProjectWise results in a pdf and all works fine.
Any help welcome!

Thanks in advance,
Yvonne