Hello @jianfromnag,
Welcome to the Klaviyo Community!
I hope you’re loving the universal block as much as I am! I haven’t heard of any issues pertaining to the Universal Blocks not saving right now and just to confirm, I was able to apply a dynamic abandoned cart block via a universal block in my own test account without issues.
Have you tried updating and saving your template using a new incognito browser? Sometimes caches and cookies or browser extensions will cause some problems in how Klaviyo behaves. Saving templates is one of them. You can also try clearing your caches and cookies and restarting your browser to see if that helps!
If the issue persists, I may also advise reaching out to our wonderful Support colleagues to see if they can offer another set of eyes.
Another thing that comes to mind as to why the template isn’t saving is that your template could be effected by some third-party syntax or variables that aren’t recognized in the Klaviyo template. An example of this would be using Shopify template specific syntax in your Klaviyo emails.
I hope this helps!
David