Editor: Blocks set to Sticky don't work in Template Parts

[kspilarski]

Description

Setting a block to Sticky does not work if the block is included in a Template part.

Step-by-step reproduction instructions

1. Go to the Site Editor.
2. Add a template part like the Header.
3. In the list view, expand the Header (template part), then set any block under it to sticky and save.

Screenshots, screen recording, code snippet

Under the Header template part is the "Header" block which is set to sticky:

Scrolling down the front page doesn't make the Header stay put., even it was set to sticky.

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But when a block is not included in a template part, setting the block to sticky works fine:

Environment info

• WordPress 6.6.1, Gutenberg 18.8.0
• Twenty Twenty Four theme
• Chrome 126, MacOS 14.6

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

[carolinan]

Hi!
This is issue has already been reported, so I am closing it as a duplicate. You can continue the discussions and follow the explorations here:
#56147
#47043

Meanwhile, there is a trick that you can use, and that is to add a new group at the top of the template, make it sticky, and place the template part in the group instead.