You’ve just unblocked someone on LinkedIn—perhaps by accident, or perhaps to check if they’ve calmed down—only to realize you need to block them again immediately. You head to their profile, click "More," and suddenly, the "Block" option is nowhere to be found.
Members You Manage: If you are a group admin, you cannot block a member of your group until you have first removed them from the group. The Invisible Timer: A Guide to LinkedIn’s "Unblock"
LinkedIn purposefully avoids publishing precise cooldown durations and internal rules to prevent bad actors from gaming the system. Revealing exact thresholds would enable manipulative behavior, so users see only the effects, not the internals. Hard refresh the page (Ctrl+F5 on desktop, not just F5)