If your site is connected to more than one Guesty account, the 3D Tour button may appear on listings from only one of those accounts.
Why this happens. Each Guesty account defines its custom fields separately. A site connected to multiple accounts has one copy of the field per account, even when the field name is the same across all accounts.
HomeRunner Toolkit 3.321.3 or later. Enter the plain field name (for example matterport_id) in Hub > Photo Gallery > 3D tour field. This works across all accounts.
Older toolkit versions. Prefix the field name with hcf_ (for example hcf_matterport_id). This reads the merged copy of the field that HomeRunner maintains for every listing, regardless of which account it belongs to.
YOOtheme dynamic content picker. Select the Property Custom Fields entry rather than any entry marked (Deprecated). The deprecated entries are the per-account copies.