Problem after moving to a new host

I just moved to a new host last week, which involved backing up cPanel and importing it to the new host & WHM. The multisite does subdomains and worked perfectly on the old host. I’ve noticed some problems:

1) When I create a new networked site, I can’t access the new subdomain. Whether I try to access subdomain or the dashboard, the url becomes /wp-signup.php?new=subdomain and the page has the message

You are logged in already. No need to register again!
The site you were looking for, https://subdomain.mywebsite.com/, does not exist.

2) Two networked sites that worked fine on the hold host cannot see new plugins I’ve installed after the migration and both have ‘Upgrade network’ notices even though the network has been upgraded (multiple times to see if the message would go away). The only connection is that both site were originally standalone WP sites whose content was imported via WordPress’ .wxr