Photo upload to Facebook Business Page failing

Hi,

for the past few weeks I have been unable to upload photos on my Facebook Business page when working in Business Suite. If I do an immediate post it works, but when working in the area that allows you to schedule it doesn't. No error message, photo just doesn't appear. Not having problems on my personal FB.

Using OSX El Capitan 10.11.6, latest relevant version of safari 11.1.2, uninstalled Adobe Flash (why do FB advise to update to new version when it's been decommissioned??)

Most grateful for any advice on how to proceed.