[DaveL]

Your set up is hard to follow. This is a problem for others trying to help, but more important its hard for you and your team to understand, troubleshoot and fix.

To make thinks easier for everyone, establish some color coding standards.
For example, you can use white tubing for the high pressure line. Then use green tubing for air that extends the piston and blue tubing to retract the piston.

That said there are way too many connectors and air lines.
Step 1. Simplify by only using 1 air tank.

Step 2. The regulator looks like it has 2 output pipes.
I have not seen this done. My suggestion is to cap the bottom opening.

Step 3. From what I can tell, air to push the piston is being sent from the 3rd valve (top) and air to retract the piston is being sent from the 2nd valve (bottom). You want to use one valve per cylinder.

To clean this up....
Remove all the tubes to the valves system except 1 providing air, 1 pushing the piston and 1 retracting the piston. All the other ports should be capped. Use a tee fitting and a loop of tubing to build the cap.

Flow limiting connectors can hide what is happening. I would replace these connectors with plain connectors. Once you understand how things work, try one before adding a second, as it might not be needed.

After you make these changes, take another picture but this time make sure all the tubes are visible, so we can help you trace their path.

Pneumatics is fun. Like programming, keep it simple to make it easy to understand.

Dave