That's a frustrating issue! What you're seeing — the image disappearing when you enable the Sequence option on an attachment inside a skin placeholder — is a known quirk of how skin placeholders and sequences interact.
Why this happens
When an attachment lives inside a skin placeholder, it is only visible when that skin is active. The Sequence feature works by referencing a numeric series of images sharing the same base path. When you enable Sequence on a placeholder attachment, the path and frame reference can lose its binding in certain editor versions, causing the attachment to appear blank or invisible even though the skin is still active.
Things to try
Check the image path carefully. When Sequence is enabled, the path field should be the base path without the frame number. For example, if your images are myimage0, myimage1, myimage2, the path should be myimage and the sequence range set to 0–2. If the path still includes a number suffix, the editor may not find the base image and will show nothing.
Try setting the attachment up outside a skin placeholder first. Place the attachment directly in the slot (no skin placeholder), enable Sequence, verify it works correctly, then move it into the skin placeholder. This can help rule out whether the issue is with the sequence setup itself or with the placeholder interaction specifically.
Make sure the active skin is set before testing. Since attachments inside skin placeholders are only visible when their skin is active, double-check in the Skins panel that the correct skin is active while you are testing the sequence in the editor.
Re-enter the image path manually after enabling Sequence. Sometimes toggling the Sequence checkbox clears or resets the path field. After enabling it, try re-typing the base path to restore the reference.
Duplicate the attachment for each skin. When creating or modifying the skin placeholder, using the Duplicate attachments for each skin option ensures each skin has its own copy of the attachment, which can avoid situations where the reference goes missing.
The Sequence feature is documented here: the path should be the full path without including the numbers, and the sequence range specifies which numbered frames to include — https://esotericsoftware.com/spine-regions.
If none of the above resolves it, sharing the .spine project file (even a minimal reproduction) would make it much easier to pinpoint exactly what is going wrong with that specific editor version.
