Hi, Yuki.
I looked through our internal bug log and found just one regarding ACF:
wp-admin event edit screen > ACF Pro (Advanced Custom Fields Pro) time picker field breaks:
- Install and activate ACF Pro
- Go to Custom Fields > Add New and create a new field group with a Time Picker in it.
- Set the field group location to “Post Type is equal to Event” like this > https://cloudup.com/cAD4TTbyXlf
- Save the group field
- Go to add or edit an event and you will find the time picker field from ACF breaks.
Is this known issue exactly what you’re experiencing?
It was logged several months ago so if it’s not, please let me know. Additionally, Then, please share your System Information (while in Testing for Conflicts Mode) in a Private Reply. That will give me a lot of extra information to help troubleshoot this.