Unable to set DataGridViewCheckboxCell to Checked in DataGridView in a TabControl

I also encountered the same issue.
I noticed that selecting the tab a couple of times on which the grid is present enables to check the checkbox on the grid. So if that tab is not your default tab while loading the form, you can switch it a couple of times between the default tab and the tab with the grid by assigning the index of both the tabs.

eg:

tabcontrol1.selectedindex=5 'index 5 is the tab with the grid
tabcontrol1.selectedindex=0 'default tab on load
tabcontrol1.selectedindex=5
tabcontrol1.selectedindex=0