Expression Tag not updating?

This has happened before but the last time I just created a tag in the plc and logged it with a transaction group. So the problem was solved, however I need to do it again and I could create another tag in the Plc and not have to worry about it. BUT, I would like to know why this is not working.

I have an expression tag that just adds 4 MQTT tags together. So it would look like this.

Expression Tag = Tank Total

The expression tank1 + tank2 + tank3 + tank4 - (these 4 tags update every 3 minutes)
I want to store the Expression Tag(Tank Total) into a transaction group.
I only write this once every 24 hours

What is strange is that it works most of the time but about ever 4th or 5th day it only has the total of tank1 as the Tank Total. And then it will work again for a few days and then tank 1 will be the only value in tank total.

Anybody have any ideas on what I might be doing wrong?