On social media Wednesday night, as the game between the 76ers and Oklahoma City Thunder pressed on, Streeter posted a 10 second video detailing what happened.
"I'm at the 76ers game singing the national anthem and the organization is telling me I can't because I'm wearing a 'We Matter' jersey," Sevyn said.
Streeter spoke more about the incident to a New York radio show Thursday morning.
"I was about to go out and sing the anthem that I've done a sound check for and everything and they just come in and tell me that I cannot wear that shirt while singing the national anthem at this game," Streeter siad.
Streeter told the Associated Press she was never given a dress code.
She was offered a 76ers jersey to wear, but declined.
So the team brought in a member of the 76ers Dance Team to sing the anthem.
The 76ers organization sent the following statement to Action News Wednesday night:
The Philadelphia 76ers organization encourages meaningful actions to drive social change. We use our games to bring people together, to build trust and to strengthen our communities. As we move from symbolic gestures to action, we will continue to leverage our platform to positively impact our community.
Streeter, meanwhile, released another message on Snapchat.
"You want me to sing about the land of the free, but you don't want me to speak freely," Streeter said.
Streeter could be seen and heard practicing the anthem during Action News sports reporter Jeff Skversky's game preview.
There was even a contest where fans could sit courtside with her during the third quarter of the game. Fans could enter the contest using #SevynSixers on Twitter.
Legal experts tell Action News this is not a civil liberty issue. It did not involve a government or happen in a public place and the team has the right to control its message.
A source says Streeter was hired under a contract that does not allow the performer to use the team to further a personal agenda: political, social or commercial.
At practice Thursday, 76ers head coach Brett Brown said the issue was discussed by players.
"I think right now everybody is learning what's going on, trying to gather information. Clearly, our players are concerned and we hear them," Brown said.
The singer from Orlando, Florida has written songs for Chris Brown, Brandy, Alicia Keys, and more, according to her Facebook page.