In the "Settings" section of Tab Session Manager there appears the following setting
What happens when you checkmark that setting and then try importing? (It appears to be 'unchecked' by default.)Supports Tree Style Tab
Restore tree state of Tree Style Tab.
When this option is enabled, it takes time to restore the session.
Supports Tree Style Tab
Delay when tree restoration (millisecond)
To restore the state of the tree, wait time is required to open the tab. Increase this value if the tree is not restored correctly.
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