Student To Do List Error - Not showing all missing assignments

For some reason, I have a few students whos To Do list is not counting assignments correctly.  

The students go to canvas - then to dashboard view.  They mostly use the "List View" in the dashboard.  The Bell Icon usually shows the number of missing / overdue assignments.  However that number is not showing the right number for all students all the time.  

Ie student 1 - when they go to canvas - it shows 28 assignments past due.  Then they click into the class; then if they click the dashboard view - it now only shows 10 missing assignments (when it should be 28).  

HOWEVER - if the student goes to canvas - it shows 28 assignments past due.  Then they click into the class; then use the browser BACK button - it shows 28 - which is correct.  

I am not sure why when students click on the "dashboard" it is pulling a different cache.  

It does this on both mac and pc using different browsers.  

I am not sure if it is related - but I have noticed a similar issue with my gradebook.  When I go into my gradebook - it generally shows my last save settings which is missing assignments. 

When it works right - it shows the students with missing assignments.  

However this week - the gradebook shows missing and no students.  Then I have to unselect missing and reselect missing - then it works right showing the students with missing assignments.  

It almost seems like theres a bug where the to do list and missing assignments being pulled is not working all the time.  

Any advice?