Celtic claim a fee was agreed with Manchester City for John Guidetti prior to them taking the striker on loan.
Xabi Alonso claims no Premier League offers were put to him before leaving Real Madrid for Bayern Munich.
Cywka's current deal expires this summer and the Tykes were keen to tie down the Pole to a new contract.
However, both parties have failed to agree terms and the 25-year-old seems set to leave on a free transfer.
The news is sure to alert a host of clubs to the availability of the former Wigan and Derby man.
Cywka made 52 appearances and scored eight goals during his two-year spell at Barnsley.