Issue with dispensing and detecting detergent levels in LG Washer

Brand: LG
Model Number: WM4500HBA/00
Main Symptom: Detergent Dispenser not working
What happens & when: The washer has a detergent dispenser that holds enough Laundry detergent and Fabric softener for multiple loads. Laundry Detergent stopped telling us if empty, and Fabric softener does not appear to be used any more (despite the setting on a “2” for use).

I have two issues, possibly related:

On the Laundry detergent side of the dispenser tray, all of a sudden, it will no longer alert us if the detergent needs to be refilled.

And on the Fabric Softener side, it does not appear to be using ANY fabric softener as the level never goes down (despite the setting being a 2 out of 3 bars for fabric softener to use).

Given these two issues - where it will not pull fabric softener, and not tell use when Laundry detergent is out, and happened at the same time starting last week - the only commonality we can think of would be some kind of control board issue.
Thoughts? It could be that the FS fill tube is clogged… But at the same time the LD side decides not to notify us any more if it needs a refill? Sounds like a logic issue if these two issues developed at the same time.

So far, I have taken out the dispenser tray, cleaned it and ensured the ends where the detergent dispenses works well (open/close).

If a PCB Board to replace, which one for this model? There appear to be many boards for this model.

Appliance Parts Pros link to washer parts: OEM Lg WM4500HBA/00 Parts | Diagrams, Videos & Repair Help

Error Code (if any):
Parts or tests already tried:
Photos / video link: OEM Lg WM4500HBA/00 Parts | Diagrams, Videos & Repair Help

It is possible that the Sub-PCB is not sending voltage properly or is not communicating with the main control properly. With the power supply cord unplugged, the detergent/softener pump can be tested using the wires at the Sub-PCB after removing the top panel. There will be a 6-wire connector with two rows of 3 wires or empty ports side by side. With it disconnected from the Sub-PCB, the orange wire at pin 2 and the brown wire at pin 5 can be tested for resistance. It should measure between 22-42 Ohms. There will also be a yellow 4-wire connector that can be inspected for any loose connections or damaged wires. The wires can be traced to the dispenser housing and inspected as well. If these things all check good, the Sub-PCB is the most likely cause of failure. Here is a picture of the Sub-PCB connectors as well as a link to the part information page. EBR88051101 Power Control Board Assembly | Genuine Lg OEM In Stock