Messages (iMessage / iChat) on MacBook Pro isn't loading old messages

Hello,

Let me start by saying that I am currently running an old version of iOS (10.14.1) on my MacBook Pro (15" Late 2011). I prefer to use this version for now. I have been using Messages and everything has been fine for a couple of years. Today, when I opened Messages all of the messages were there but I noticed that when I received a text that it would update on my iPad and not on Messages on my Macbook. I figured that I would log in and log out and when I logged back in all of my messages are now gone. I notice that if I type a word in the search that old messages with the word will appear but once I clear the search there isn't anything there but a select few messages from today that I received.

• I have signed out on my iPhone and signed back in.
• I have selected and deselected the receive text messages option on my iPhone.
• I have deleted the password from the keychain: "com.apple.facetime: registrationV1"
• I have restarted my MacBook.

Maybe there is a specific order to something that I am not doing. Or, maybe there is something that I am plain out not doing. Please help. Thanks in advance!