It seemed to work for me: 86,601 POIs. Too big to attach.
Can you describe the exact procedure, please?
I tried unhiding, for instance, four pushpin sets. Then I clicked on the word "Pushpins" at the top of the list to select it, then I clicked the Export to Excel icon on the top toolbar. Nothing.
The only way I can find to get the export to work is to actually select one of the pushpin sets in the list, e.g. click on on pushpin set name so it's highlighted. But that only results in that one set getting exported, no matter how many sets I have unhidden.
After you did the unhide for all sets, what exactly did you do next? What did you select/highlight? Etc.