If you make it your business to be a professor that teaches at a university here are a few tips for you

respond to student emails. 
respond to them with politeness, especially when that student went out of their way to sound polite and inquisitive about a situation YOU created.
if there is a problem with an assignment that was periodically graded over a 15 week period and you couldn't take the time to actually view the assignment to know there was a problem, don't make it the students fault. especially when it's a browser issue that seems to have only occurred on your end.
don't make sassy, unnecessary remarks in reference to aforementioned questions. this is my grade that determines if I graduate or not. I have a right to know when things will be updated.
if you expected to hear back from me within an hour before submitting an incomplete grade for an assignment you graded at 100% for 15 weeks, but can't respond to my email in three weeks, then you need to reassess your career. i'm an adult who paid you to teach me something. i'm an adult who spent hours of work time under your "guidance" and it is your responsibility to keep your students informed about an issue that you've caused. 


summary: uni professors can be dicks.