The phrase "due to a schedule conflict" is correct and usable in written English. You can use it to indicate that an event or action is not able to take place because of scheduling difficulties. For example: "I'm sorry, I won't be able to come to your birthday party due to a schedule conflict.".
(I was not able to attend the Zep event in person, due to a schedule conflict).
Due to a scheduling conflict, the chat has been postponed.
"It was postponed due to a scheduling conflict," said James Jordan, the committee's executive director.
Cotillard has been forced to quit production of the untitled project due to a scheduling conflict.
** UPDATE: This chat has been cancelled due to a scheduling conflict.
UPDATE: This chat has been cancelled due to a scheduling conflict.
A press representative for "The Anarchist" said that Ms. Metcalf had withdrawn due to a scheduling conflict.
Ludwig does not simply clarify my doubts with English writing, it enlightens my writing with new possibilities
Simone Ivan Conte
Software Engineer at Adobe, UK