I have a calendar set with a column link to set the primary key and date fields on another page using #PRIMARY_KEY_VALUE# and #DATE_VALUE# on the calendar page. This is not always working, sometimes it is fine and other times the session PK on page 2 is being RESET_TO_NULL. I am using apex 4.21.00.08 version. Also, this only seems to happen on IE 8, I tried it on Firefox and I have not had it reset the PK when the page renders. Has anyone had similar issues?
It may very well be just a problem with that decade old browser. While the APEX documentation suggests development from IE7+, you simply won't get all the features from non HTML5 compliant browsers.