Schedule block preview is not refreshed when using the Now marker.

Steps:
1. Create new LP.
2. Add Schedule block.
3. Add content.
4. Move timeline slider few hours into the future.
5. Remove content.
6. Click the Now marker.
Actual: Preview is not refreshed, content is still not visible.
Expected: Preview is refreshed and content is visible.

Remarks: However preview is refreshed when slider is moved at least by one minute.