Conversation so far:
What happened witht the Incredible String Band in 1971?
Rose Simpson left The Incredible String Band in 1971 and Mike Heron took time out to record a solo album.
Why did Mike Heron take time off from the Incredible String Band?
Mike Heron took time off from the Incredible String Band to record his solo album Smiling Men with Bad Reputations.
Was Mike Heron successful with his album Smiling Men with Bad Reputations?
Mike Heron's solo album Smiling Men with Bad Reputations was well received.
Did Mike Heron return to The Incredible String Band after recording Smiling Men with Bad Reputations?
Mike Heron returned to The Incredible String Band and recorded a few more albums which were received disappointingly. Island Records dropped them in 1974.
Were the Incredible String Band's final albums for Island successful?
The Incredible String Band's final albums for Island were received disappointingly, and the label dropped them in 1974.
Are there any other interesting aspects about the Incredible String Band besides their records and solo projects?
The Incredible String Band's final albums for Island were received disappointingly, and the label dropped them in 1974. By then, Robin Williamson and Mike Heron had disagreements between them

Question: what were their disagreements?
Self-contained rewrite: What were the disagreements between Robin Williamson and Mike Heron?