Possibilities
Suggest that the posts by Ianab, Husky137 and John Ellison are very appropriate.
Several items can be a factor in barber chairs:
Shallow and/or narrow face or no face at all,
Too deep a face on tree that is about ready to go,
Back cut not at correct height to face,
Not using either a “triangle” or the preferred plunge back-cut,
Face cut ‘matching up’ with a split in tree,
Driving Wedges too hard or unnecessary wedging,
Wind,
A second tree leaning into the one that ’chairs,
Additional weight added up in a leaning tree,
Pulling a tree with a rope or cable too hard,
Improper hinge wood width,
Failing to nip corners or bore out center of hinge,
Not placing chain(s) with binder(s) on truly severe leaners,
Defect in tree,
Dull chain or running out of gas in middle of back-cut.
Any chance you could get some photos?