Depending on exactly how you have Sonarr set up you may be falling foul of the behaviour mentioned in the Caution in this section of the online documentation accessible via the Manual link at the bottom of the Unraid GUI. In addition every forum page has a DOCS link at the top and a Documentation link at the bottom.
The easiest solution might simply be to set those shares up as Primary Storage=cache, Secondary storage=array, mover direction= cache->array.