said 9 months ago:
Is your Page connected to your personal account? If it is, you need to be logged into your personal account in order to have the invite friends option. It’s a little odd considering you can only have one personal page connected, however…
While logged into your personal account, click “facebook” in the upper left hand corner so you’re looking at just your news feed. On the navigation bar on the left there should be a section that says “Pages and Ads”, under there should be a list of the Pages you admin. Click on the Page you want to invite friends to. When the Page loads, it should say “You are Posting, Commenting and Liking as Trish Ledingham – Change to Trish Ledingham”. If this is showing you’re in the right place, if not, follow the instructions above again.
Now, under “Build Audience”, it should have “Invite Friends’ as an option. If it doesn’t you’ll need to submit a bug report - https://www.facebook.com/help/contact/164405897002583