Webform custom option buttons gives plugin missing error when it is made required on condition

How to reproduce error?
Fresh installation on 8.8.2 and webform 8.x-5.x-dev

Testing Example: Elements: Condition Logic webform
Create a custom buttons in this test form and is required based on another element selection.

They work well on their own but if the become required based on simple condition it gives error.

Thanks for your great module once again.

MkSamy

The example form yaml.

checkbox_example:
'#type': details
'#title': 'Checkbox example'
'#open': true
checkbox:
'#type': checkbox
'#title': 'Please check this box'
test_custom_buttons:
'#type': 'options_custom:buttons'
'#title': 'Test custom buttons'
'#options':
'Test one': 'Test one'
'Test two': 'Test two'
'Test three': 'Test three'
'#states':
required:
':input[name="checkbox"]':
checked: true