Reigning European champion Natasha Gale has been suspended by GB Boxing because of "unacceptable conduct" and will not defend her title next month.
Gale has been left out of the seven-strong British squad for the event, which begins on 5 June in Sofia.
BBC Sport understands there are worries around middleweight Gale's behaviour towards her team-mates and staff.
"There's a disciplinary process ongoing," GB Boxing performance director Rob McCracken told BBC Sport.
"Natasha had a difficult Commonwealth Games and it's around conduct and interacting with her colleagues. It probably reached the point where it was deemed unacceptable by the programme."
Gale won gold at the last European Championships in her first appearance at a major international event.
However, at April's Commonwealth Games on the Gold Coast she was eliminated in her first fight.
"I feel this is better for her and the team at the moment," said McCracken. "But there's a way forward and hopefully she'll be back in the programme.
"The journey of a boxer is difficult and Natasha is relatively new to the sport but we'll make the right decision what's best for everyone shortly."
Among the boxers heading to Bulgaria are Commonwealth Games champions Lisa Whiteside and Sandy Ryan of England and Wales's Lauren Price.
Commonwealth silver medallist Paige Murney, Ebonie Jones, Karriss Artingstall and Demie-Jade Resztan complete the team.