It looks like
your OST file had become inaccessible; you may need to convert your OST file to
PST. After synchronizing once with your exchange, you can recreate
your OST again from it
For this you
can try OST to PST conversion software like SysTools OST to PST Converter, Stellar,
PCVITA, Kernel and many more, which allows converting OST file into PST
providing access to inaccessible data.
I hope it would help you.