Joseph Priestley is often said to have discovered Oxygen, or not due to calling it Dephlogisticated air - depending on one's preference. However, regardless of this, it is often said in popular accounts, such as Wikipedia, that due to his continued use of the theory of Phlogiston, he became isolated from the rest of the academic community and the chemical revolution.
I have read some of the works of Priestley, and the related work on Cavendish - who used the Phlogiston theory up to the late 1700s. It is reported in Wikipedia that in 1787 Cavendish was one of the first people to use the Oxygen theory outside of France. The riot that burned Priestley's house was in 1791, and Priestley moved to America in 1794 as a result of his political disagreements. He rapidly became friends with Franklin (perhaps due to his work on electricity, but I have not read up on that). He became ill in 1801 and died a few years later, and before that was simply hampered by lack of contact with the scientific centers in Europe. On the other hand, he was connected to Franklin.
This does not feel to me as though Priestley became scientifically isolated due specifically a unique (others also defended the theory) tendency to support Phlogiston. And indeed no more isolated than would have been likely due to events in his later life. The isolation, such as it was, seems not to have been long, and not really to have related simply to support of the Phlogiston theory.
Are there more details that can be added to support the suggestion of isolation due to support of the Phlogiston theory?
I mention Cavendish in respect of 1787 being the first used of Lavoisier's theory outside of France. Hence, giving a timeline for the acceptance. Further, having read some of Cavendish's papers of the time, I see that he actually supported the Phlogiston theory over Oxygen - for entirely pragmatic reasons. Cavendish was reclusive, and I do not put him there to counter claims of Priestley isolation - Priestley was well published and otherwise connected. On the other hand Cavendish also was an FRS and did attend dinners regularly, even if he would not look at anyone. So, I would not describe Cavendish as isolated. (Thanks to @Conifold for bringing up this issue).