If I remember rightly it was actually one reporter that was banned because he publicly said, after a fine by UEFA for sectarian singing, that Rangers were not actually serious about banning certain songs and one director had said 'The Billy Boys' was one of his favourite songs. The BBC then stopped sending any reporters to Ibrox as a protest.
No doubt they have now come to an agreement as the reporter concerned no longer works for the BBC or something similar.
UPDATE : Here is a watered down version of original story not actually mentioning what he said:
https://www.dailyrecord.co.uk/news/scottish-news/bbc-refuse-send-staff-ibrox-6179565