I am running the piwik 1.9.2 on my server but I do not see any custom variables in the visitor log - scope "page" - also not as an tooltip. There is only the tooltip shown how often the page was visted, if the page was visited more then once.
In the piwik modul "custom variables" the variables are shown correct so that the bug should somewhere in the vistor log.
So it is hard to analyze the vistor actions compared to "GET"-formulars.
Setup is here:
Keywords: custom variables visitor log page
Attachment: Screenshot Visitor Log
Attachment: Screenshot modul custom variables (working)
I notice that the custom variable is not displayed if the value is empty.
However the bug you report, is because the tooltip shows the custom variables for the "first unique pgaeview". When pages are collapsed and 2X is added, the first tooltip remains (so maybe you dont set your custom variable on the first page view?)
(In ) Fixes #3590 Display custom variable tooltip even if custom variable value is empty