Scotland have just one win in their last 15 games following a 2-1 defeat away to Croatia in the Nations League.
Ryan Christie had briefly given Steve Clarke's side the lead in Zagreb.
Che Adams had an injury-time equaliser ruled out for offside following a V-A-R check.
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Northern Ireland missed the chance to top Group C3 in the Nations League with a goalless draw with Belarus.
The result leaves Michael O'Neill's men trailing last night's opponents and Bulgaria by a point in the table.
They next face the latter on Tuesday in Belfast.
