What causes the issue?
The issue is most likely caused by server-side caching, which can cause this type of odd behavior.
How to fix the issue
Step 1: Contact your server host and ask them to exclude the PopupAlly Pro styling file from the cache.
The file you will want them to exclude is:
After you’ve contacted your server host, check the page using an incognito browser. Check the page while you’ve still got your server host on chat or the phone, that way if it’s not resolved you’ll still be in contact with them.