If you want to enter values greater than 10,000 hrs enter them as text strings
Then do the math with formulas and add them Hrs, Mins and Secs together
eg:
This is what i am doing currently. I was looking for something which stores it in Time format in the first place. We need to frequently import/copy-paste data which contains values 10K+ hours and then perform further calculations based on them. For this it requires to find those mischievous values and give them a spanking with help of TIMEVALUE function.
Not sure if this is a bug with Excel or something else.