A question for Docking experts

In my latest endeavors I docked a large fuel stage, unmanned, behind another fuel stage attached to a habitation module also using a command module. I successfully dock.
Also docked is a CSM style capsule, manned.
I maxed out the magnetic force on all docking rings.

I launch a third ship, a refuel ship, unmanned, using a command chip, and rendezvous with the other above described docked combo.
When I get within 10 km the combo detaches all docked ships and all 4 float away from another.
At 10 km, I noticed the Sim will skip a frame, so-to-speak, to load the actual image rendering of your target appears.
Also the uncontrolled unlocking fiasco will happen if I save and then reload. Also if I use to slow-mo button.

What is happening here? Is this usual? Is there settings one must look after to prevent this? Is there any guide to show the laws of Docking parts?
Can anyone help?

So far I have been able to narrow the issue down that its two ships that use a command disk instead of capsule where the docking ports bounce.

If anyone has had this issue and know of a solution, I would be grateful to hear it. :-)

Thank you for your response.

Yes. I already have docked 3 CSM style ships to the Station. Its the Unmanned drone re-fuel ships that bounce off the docking port.

I am actually well practiced at Docking.

On one occasion, I had no other ships docked. I brought in a the re-fuel drone, docked, started to re-fuel then is bounced right off with a recoil of 1.25 m/sec. Docked again, same thing.

I have been able to re-fuel on prior missions successfully and do a complete re-fuel, but then one or two of the other Docked ships would separate when I hit the slow-mo button.

I once was able to get two Re-fuel drones docked at the same time, but only once.

Please see my latest screen shots on my profile for a quick visual. https://steamcommunity.com/profiles/76561198064777201/

I also renamed every docking port to have their own unique name.

I wonder if there is a limit to the number on ports a ship can have?
Or if there are some ship settings that need tweaking?
Or may be I should rebuild these from scratch to eliminate any settings contradictions as I evolved these ships?

Again, any insight would be fantastic.

Cheers

P.S. Last night I did try to dock two Re-fuel drones together, one with a standard port, the other with an improved port. The two would not dock as if they did not even have the port part. Also, the standard port, when targeted, produced the docking cone imagery, but when I switched ships and targeted the one with the improved port, the docking cone would not appear. When using the ship with the improved docking ring. the docking HUD showed the docking ring to a +15.75 meters in front of the zero point when the two docking rings touched.