Blues target Bersant Celina is sidelined with heart complications related to Covid-19.
As previously reported, Town have been in talks with the former loanee, who is currently with French side Dijon, about a return to Portman Road for much of the summer.
The 24-year-old contracted Covid late in June but returned to his club in mid-July.
However, manager David Linarès says the Kosovo international is currently not involved due to a heart issue.
"Bersant Celina has a problem related to Covid-19, complications at the heart level,” Linarès told his club’s official website. "We must not take risks.”
Celina is required to undergo tests before he is able to return to action with Dijon, who were relegated to Ligue 2 last season.
The former Manchester City man’s lack of involvement in pre-season and likely continued absence for some weeks would appear to end any chance of Celina returning to Portman Road this summer.
Town were facing opposition from a number of other clubs for the forward's signature, reportedly including Championship Hull City and Coventry City, and clubs in the Dutch top flight where Celina previously played on loan with FC Twente in 2016/17.
Celina spent 2017/18 on loan with the Blues from Manchester City, making 26 starts and 12 sub appearances, scoring eight times, in a successful spell under Mick McCarthy’s management.