To fix the Save Changes not working with WPBakery Page Builder when using WordPress 6.11 you need to install the Enable jQuery Migrate Helper plugin as well. The Save Changes should then work.
Must change all the portfolio items into posts with a plugin “Post Type Switcher” before switching the theme then switch them all back to being portfolio items. Scalia has a different enough portfolio system for them not to transfer across otherwise.
Where there are Owl_Slider widgets on a page can be better to delete everything and start again but:
The best way:
Activate the Voxco Framework Plugin so that the Owl Slider elements show in the backend editor.
Make notes in a word processor page of all the names of the .jpg images referred to in these elements where abouts they are on the page.
Delete the Owl Slider elements.
Deactivate the Voxco Framework plugin.
Refresh the back end.
View Portfolio Item to check that the bracketed shortcodes are gone.
Add Single Image elements as replacements with Full size and centre alignment.
Check front end.
This actually creates more problems because when turned on it slows down this blog when using the Scalia theme:
When “Load CSS Asynchronously” is turned off the page is rated a B instead of a C. (This is the case with Voxco theme with Litespeed Cache without Cloudflare, with Cloudflare this combination the rating seems to stay the same. With the Scalia theme without Cloudflare similar negative effect of altering Litespeed in this way but ustilizing Cloudflare as well it goes from a B to an A). Cloudflare itself has no influence except for minification. See here