The cause was that the information remained in Rows Disabled of Track even though it returned to one Track by the delete operation from the state where there was a child Track of multiple rows.

As a result, the result of Track->IsRowEvalDisabled will be unintended. For example, SSequencerSection :: OnPaint.

As far as I've investigated, the following fix code can solve this issue.

// add
MOVIESCENE_API void ClearRowEvalDisabled(); 

// add
MOVIESCENE_API void UMovieSceneTrack::ClearRowEvalDisabled()

void FSequencerTrackNode::UpdateInnerHierarchy()
const int32 MaxRowIndex = Track->GetMaxRowIndex(); 
if (MaxRowIndex == 0) 
   // Single row, perhaps with a top level key area 
   if (SubTrackMode != ESubTrackMode::None) 
      RequestReinitialize(); SubTrackMode = ESubTrackMode::None;
      // add 

Steps to Reproduce
  1. Add two Audio track
  2. Mute the first track
  3. Delete the muted track

expect : the remain track is not muted
result : the remain track is muted, and user can't unmute it

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ComponentUE - Anim - Sequencer
Affects Versions4.27
Target Fix5.1
Fix Commit19373982
Main Commit19402242
CreatedFeb 4, 2022
ResolvedMar 14, 2022
UpdatedMar 16, 2022
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