Blisk tablets list is a group of devices, located in the browser devices list. Read more about browser devices list here.
If you can not find the tablets list - it might has been collapsed. Find the tablets toggler on the top of devices list. Clicking this button expands/collapses the list of browser tablets. The indicatormeans, that the list is collapsed. The indicator means, that the list is expanded.
Please note, that if you collapse tablets list - Blisk will save it's state. It means that if you open the new tab or a new window - the tablets list will be collapsed.