QSqlTableModel query filter fails to return any records when it should

In QSqlTableModel using SQLITE 3.27.1, I set the filter to:

filter= "[dancegroupname] = 'American Smooth' AND [dancename] = 'Waltz'"

where dancegroupname and dancename are TEXT fields in songfiletable.

When I setFilter(...) and select(), I get no records. There are 2 records in the database table which meet the criteria; they are not returned. This is a bug.

More information: If I code the filter with "like" instead of "=" using exactly the same query values, 2 records are returned:

filter= "[dancegroupname] like 'American Smooth' AND [dancename] like 'Waltz'"

I coded a test query (in the same project) using the same database and table. When I  execute the test query (logically equivalent), the 2 records are returned:

executed query: "SELECT * FROM songfiletable WHERE [dancegroupname] = :a AND [dancename] = :bb;"
Query.prepare(sqlPre);
Query.addBindValue(P_dancegroupname.toUtf8());
Query.addBindValue(P_dancename.toUtf8()); 
rc = true and records are returned.

More information:

I opened a terminal window and ran sqlite3.exe with following query. It returned 2 records (as expected). I used "like" instead of "=" because the "=" query failed to return any records.

sqlite> select songfile_id,dancegroupname,hex(dancename),length(dancename) from songfiletable where dancegroupname like 'American Smooth' and dancename like "Waltz";
songfile_id|dancegroupname|hex(dancename)|length(dancename)
382|American Smooth|57616C747A|5
393|American Smooth|57616C747A|5