Either they are not marked as captain, or their roster spot is not linked to their account yet. On the Host Dashboard Players tab, tap the star icon on their team to check Current Captains. Then make sure they have signed in and claimed their spot (for example with Claim Your Player on the event). See Assign and change team captains.
Troubleshooting team events
Most Team Event / MLP problems come from a handful of settings: captain status, lineup lock and visibility, the scoring system and tiebreaker, and what the Admin menu offers once play has started. Find your symptom below.
Captains and lineups
A captain says they don't see an Edit My Lineup button
A captain can see the lineup but can't change it
Lock lineup (prevent captain changes) is on for the division. Turn it off in Event Settings → Team Scoring Configuration, or set the lineup yourself from Edit Team Lineups in the Admin menu.
Players can't see who is playing each line
Lineups are hidden for those rounds. In the Admin menu on the MATCHES tab, open Show Lineups (it reads Hide Lineups when lineups are visible) and set rounds to Visible, or tap Show All. Rounds with scores entered are always visible. See Hide or show lineups for team events.
Schedule and lines
I changed the number of lines and every round changed
The line count is a division-wide setting, whether you change it in Team Lineup Configuration or in Edit Line Names. New lines get match slots in every round, and unplayed matches on removed lines are deleted. Matches with a score or winner are kept. To rename lines for some rounds only, change just the names in Edit Line Names and leave the count alone.
The knockout bracket has different lines from pool play
Use the same lineup for Pool Play and Knockout is unchecked in Team Lineup Configuration, so the bracket uses the lines on the Knockout tab. Check it to make the bracket mirror pool play. See Configure team lineups.
Scoring and results
A matchup ended level and shows as a tie
The tiebreaker is set to No Tiebreaker: Leave It a Tie, which is the default. Pick a tiebreaker in Team Scoring Configuration if every matchup must have a winner. See Configure team scoring.
A team has an unbeatable lead but no winner is shown
Only Total Wins decides a matchup early. Under Total Score and Individual Games the winner appears once every line is complete. Under Total Wins, check whether Only show a winner when all games are done is on.
A captain or player can't enter a score
Allow captains to enter scores or Allow players to enter scores is off in Team Scoring Configuration. Hosts and admins can always enter scores. A captain also needs a claimed roster spot.
Teams
I need to change a team's name
On the Host Dashboard Players tab, tap the pencil icon (Edit team) on the team's row, change Team Name, and save.
A team dropped out after the schedule was made
Replace the team in its matchups instead of regenerating. See Edit team matchups.