I am also experencing this issue.
In plan mode, i created a plan for a proposed change, specificly i found a function call that was incorectly named so asked it to look for any others.
it did, i pointed out some were obsolte code and can be ignored.
instead of updating the plan, the agent acted to rewrite large portions of code, ignoring plan mode.
i stoped and reverted it
Telling it to update the plan, instead it created a readme doc listing things entirely differntly to the plan.
Arguing the plan was not in workspace so cannot be edited.
I beleive this relates to this thread also: