I recently needed to create a very similar library to our existing design system, but did not need to connect them in any way from a team or enterprise perspective - but they did share common themes such as type styles, color palettes and grid.
With that, I found the “trick” where you could cut/paste all of the styles from one file to another - and at first, thought I found a real time saving hack for myself - but has since turned into a 2 week nightmare within our files.
It turns out that by ‘cutting’ any of the styles from you existing library, disconnects them from your components, and the only way to go back and reconnect the assets is by manually doing so.
About a week ago, I spent an entire day manually reconnecting the styles within a branch before reconnecting over 100+ of our components. For a few days things seemed to be working fine - but one of my designers messaged me late yesterday that the styles have seemed to have disconnect themselves again.
In the interim as well, several times when I needed to publish an update to our library, the publisher dialogue would prompt me to re-connect all of the styles yet again - even after manually reconnecting them to each library several times.
In lieu of manually going back and re-connecting these styles yet again - so we can move on with continuing our regular work - does anyone have any tips or solutions as to why this may be happening and how it can be solved? This has been a huge waste of time for my entire team and a truly unfortunate experience.

