Can't turn off "Override global build expiry configuration" in plan miscellaneous tab.

Steps to reproduce:
1) create new plan
2) go to its Plan Configuration -> Miscellaneous tab,
3) turn on (check the checkbox, set some expiry details) the "Build Expiry -> Override global build expiry configuration", save
4) turn it off, save
5b) the "Override global build expiry configuration" checkbox stays ticked
5b) where I'd expect it will be turned off