…Tonight they kept singing, so I bowed my head in order not to stare and get annoyed. The singing continued (whole group, not just the leader). When I looked up, they were still singing, but Father was back in his chair and the altar was clear. I guess he decided not to wait for them.
Since I don’t know the parish, the music group or the priest, this is only a guess based on the various parishes where I’ve worked…
Perhaps after that other mass, the priest and the music director spoke. So, on this one evening where you saw the priest sitting in his chair and not going to them, they probably worked out a way for the music group to receive communion after mass. It may not have had anything to do with the priest being frustrated or trying to teach the group a lesson. They might have actually worked it out sensibly and maturely. That’s what usually happens in a healthy working relationship - the priest would approach the music director about the last mass. He might reprimand him/her or just ask him/her what happened and suggest finding a solution to that problem.
There are a number of parishes which do this. Often times, the priest will want the organist, cantor, music group, choir, etc. to keep doing the music for communion until he is finished clearing the altar - and I’ve seen some priests become very upset at organists or whomever was playing if they did not do this or did not start the music once he received the Eucharist. In the churches where I usually work, the organ is in the choir loft way in the back. The cantor can usually receive communion before starting the hymn - unless the priest wants the hymn to start immediately. The organist, however, usually never has a chance to go downstairs to receive communion because of the how the priest(s) want the music to continue. So, they either work out a way to receive it after mass or another priest or EMHC will go upstairs to the organist to distribute the eucharist after the music is completed. It is true that some instrumentalists are very capable of playing and receiving at the same time, but some are not, so they prefer to wait until after.
When I sang in a couple of church choirs, when we were in the loft, one or two choir members who were also EMHC’s would bring the Eucharist upstairs for us and we’d receive while the organist would play something on the organ - or wait until the motet was over and we’d receive then. At another parish, the choir was up front, so an EMHC or priest would wait until the choir was completed (at the priest’s request) and distribute the Eucharist.
I think another thing to be aware of is that many of the things we see or hear the choir or other musicians do is actually at the request of the priest who is saying the mass. We have about 5 priests at my parish and almost every one have specific requests on what we must do for their mass in terms of the music - when to start, stop, how many verses, etc. So, while some may think that it’s all the musicians’ doing, it actually may be just them listening to the priest.