The choir had been invited to sing with Barry Manilow at the First Direct Arena on Saturday June 25.
Its founder said that despite not being paid for their appearance, members had been looking forward to the performance for months and invited friends and family from across the country to attend for their special song.
Lauren Elliott, 31, who is also the choir director, said they had believed this "would be an experience of a lifetime" and were "delighted to be approached".
However, she said the night ended in "heartbreak" - with many of the choir left in tears on the arena stage during rehearsals.
Speaking to the YEP, she said: "On Saturday we arrived at the arena, were taken to a basement storage room we were told was our holding area, given our choir robes and eventually taken on to the stage, after being made to wait around a couple of hours, to practise choreography.
"At that point, after being positioned and swapped around for quite a length of time on stage, a man walked out telling us they were lining us up this way for a very special reason.
"He said that Barry had decided to sing a new song tonight and therefore we would not be singing in the show at all because of the last minute set change. They never even heard us sing.
"Our friends and family had bought tickets and travelled from all over. It was literally just a couple of hours before the show was due to start that we were cut."
Lauren, originally from Leeds, started the choir in May 2022 and said it was "all about happiness, positivity and caring for others through singing".
She described how they had felt "cast aside" on the night, saying: "Barry Manilow came out to take some photos with us and we were given free show tickets but that was no compensation to us.
"We had worked so hard to sing at the arena. We were determined we were going to sing on that stage anyway though, so insisted they let us sing one of our songs to the empty arena before we were made to leave.
"This was so brave of my choir, as so many of us were in floods of tears and many of us could barely sing.
"We had no backing music so it was completely acapella and we relied on one of our members' amazing perfect pitch to give us the starting notes."
The choir decided to send a message to Barry Manilow’s team, requesting that the singer make a charitable donation to the Leeds Children’s Transplant Charity.
"We are raising funds for this particular charity at the moment by doing 100 hours of singing before we perform at the British Transplant Games Gala at the Royal Armouries in Leeds on July 31", Lauren added.
"We had hoped to contribute the rehearsals on the day of the show and our singing within the show itself to our 100 hours goal but obviously can no longer do that.
"Our request was met with silence for quite a few days but last night Barry donated £500."
Lauren said the choir - who had been due to sing Let Freedom Ring and It's a Miracle -had hoped for a "little more generous donation" as their expenses had soared in recent weeks to reach the show.
"Regardless though, I think the fact Barry has now acknowledged the hurt that was caused, will bring a little closure for us, knowing this will have hopefully caused him and his team to think more carefully about the treatment of local choirs contributing to their shows in the future", she added.
"Plus, I think knowing that the donation will be going towards a great cause will help us begin to heal our own hearts, as well as hopefully helping to literally heal the hearts of some of the children supported by the Leeds Children’s Transplant Team."
Visit their website or follow @LovePopChoir to follow the choir's progress towards 100 hours of singing and to see videos from their upcoming gala.