"stamp storage page in rulebook on back of map"
This doesn't seem to be working in endless mode (but it does in 7-day mode). I tried putting some leftover stamps on it at the end of the day and confirmed they were on the page by flipping it back and forth, but the next day the page was empty. I even tried putting non-Kan-post issued stamps in it and leaving some on the table, and the ones that went into the book were gone the next day while the ones left on the table were still there.
I'm playing in a browser (Firefox, Windows 11), haven't tried the download version at all.