Wondering why less than half the lightboxes don’t support the ‘display thumbnails for your images within the lightbox’ feature?
That capability has to be offered by the authors of the lightboxes and is beyond my control. I have provided the links to each of the lightboxes’ home pages in the plugin, so you might want to reach out to them with this question.
This seems like a cool option to have, does it cause slowness or something.
Depends on the lightbox. For LightGallery it requires an additional script (you can see the script size details under Photonic → Settings → Lightboxes → LightGallery; it adds 8KB).
Is it a ‘must have’ feature or better avoided?
Depends on you. In between “must have” and “better avoided” there is also “nice to have” and “don’t care”, and it all comes down to personal preference. E.g. there is no conclusive answer to which lightbox script you prefer – it is a personal preference.
With Lightgallery how do I show my thumbnails is there a setting. I am using Media Library Assistant to select and compose my gallery. They’re not coming into this lightbox.
Use the options in the section documented above (Photonic → Settings → Lightboxes → LightGallery).
Also how can I get rid of the WordPress menu bar that’s at the top of screen. This is showing in Lightgallery lightbox is active, but not for example in Swipebox.
End-users of your site will not see the WordPress menu bar – that is only visible to users who have logged in to your site. If you wish you can disable the WP menu bar from your WP dashboard under Users → Your Profile → Toolbar
This is not an “issue”, so I am marking this “not a support question”.