What could cause "..." to be displayed in diagrams tab of web applications, when Vista displays data consistently?

Issue
When viewing real time data in the Web Applications Diagrams, a numeric object displays "..." instead of the value.
The data will show up when the diagram is viewed in Vista.

Product Line

Power Monitoring Expert 7.2.x

Power Monitoring Expert 8.x

Power Monitoring Expert 9.0

Power Monitoring Expert 2020

Power Monitoring Expert 2021

Power Monitoring Expert 2022

Power Monitoring Expert 2023

Power Monitoring Expert 2024

Environment
Web Applications Diagrams
Vista

Cause #1:
This may be caused by the ION services attempting to poll information for devices that are no longer active in the system.

Cause #2:
The name of the diagram has special characters

Cause #3:
WebReach diagrams with four or fewer objects in them will not receive real-time updates

Resolution

For Cause #1:
To resolve this, disable the devices/sites that are no longer active in the system. Devices which are not communicating are still being polled and this extra stress could cause Webreach to not show real time information consistently.
Restart the "ION XML Subscription Service" and restart the  "ION XML Subscription Store Service".

For Cause #2:
Rename the custom diagram to a name without special characters.

For Cause #3:
To work around this cause, add at least two more objects to the diagram with different measurements selected.
This is no longer a problem in IE9, so updating your browser will correct this as well. (IE8 did not properly support jQuery which is what is used by Diagrams)