He has recently returned from 2 weeks' compassionate leave, and was understood to have been reluctant to return to the Suffolk area, fuelling speculation that Jon has not settled in at Ipswich.
However if a £3million bid came in, it would definitely test Jim's desire to keep hold of the 24 year old.
Jim told Sky Sports News: "Jon is still an Ipswich Town footballer and until that changes and until somebody tells me he is not, then he is going to be treated accordingly,"
"Certainly we are in a position now at this football club where we don't have to sell our best players and Jon is certainly one of them.
"I think he could play at the next level and that is where we want to play in and hopefully he can take us there.