Numerous times during home inspections I find issues with insulated windows. Usually the problems exists and are more prone to failure on the south and southwest side of the house. Hermetic seals can fail and will require replacement.  These rubber-like seals are prone to failure with age and heat.  For some reason, small fixed windows with this type of seal also seem to be more prone to seal failure. The only safe repair I know of is to replace the failed sash. Recommend consulting a General Contractor or a Remodeling Contractor for evaluation and repairs.