CompactLogix Value changing on boot

Let me start by saying I didn't write this program, I only maintain it.

On power cycle a tag is changing it's value to a number that is not in the program from what I can tell. It only changes one value in the active recipe and then writes it to another device.

I've cross-referenced all destructive bits in the program and the value is no where to be found, only the correct value that it should be writing.

Im certain it's not coming from the device the PLC is talking to because the PLC steps on whatever I manually input into it.

I've been told it may be a default value in the EDS file that it reverts to.

Has anyone had any similar experiences with tag values being overwritten on boot with no obvious source? The SD card is not inserted in the PLC. The HMI doesnt have any Macros and the PLC handles all of the recipes.

Thank you,
MS

Is the value being referenced in the HMI at all? A memory tag can be set to fill in a value right in the tag configuration, no macro needed, iirc...

Yes the tag is used on the HMI. On the "numeric input display properties" - "connections" tab the "value" is a tag taken from the active recipe or whatever the user enters and the "enter" is a seperate tag used to write to the other device. Where would I look for a memory tag's configuration? I dont see the mystery value anywhere in my main program tags when Im online or offline, or should I be checking something in the HMI? There are no HMI tags configured in FTStudio. All tags used are from the PLC main program.

Yes it would be configured as a memory tag in FTViewME pointed at the address on the PLC, so if there are no tags configured in ME, it's not that

First Scan

If the main routine has the JSR "module read" followed by JSR "module write" is it possible that on first scan the unwanted value is read from the module overwriting the original recipe value, then writing the unwanted value back to the module?