Three things stop drawing on purpose:
- Bar replay locks every drawing while it runs. Leave replay to draw again.
- The multi-chart grid turns off new drawings.
- The locks: the lock button on the left toolbar freezes every drawing against accidental drags, and each drawing also has its own lock on its quick bar. Turn the lock off to move it.
If a drawing has disappeared rather than locked up, check the eye button on the toolbar, which hides drawings without deleting them, and the drawing's Show on setting, which can limit it to some intervals. Drawings are saved per symbol, so switch back to the symbol you drew on. If none of these explains it, report it through Reach out.