Center Brake Light not working along with rear right cargo light.

Your front signals flash rapidly because your rear ones aren't working and that is normal and shows that a bulb in the circuit is out. At least that means the problem is not with the operation of the signal....good. Also your 3rd brake light works which shows the brake switch is working. Again...good.
Everything so far points towards your rear light clusters being at fault, although both at the same time is somewhat unusual.
You don't mention rear lights that come on with headlights or the reverse and fog lights. If nothing is working I would check the earth/grounds and the connection blocks that carry the power to the light clusters, but again both at the same time being faulty is suspicious and if the reverse, fog etc is working then why not the others?
I don't know about your model, but is there a separate fuse for the rear lights that are out? Probably not but worth a check.
Have you recently had something changed on the vehicle, or inspection work done? Maybe wires/connectors/grounds etc have been damaged or disconnected/reconnected wrongly in that area.
Try running a live directly to the cluster to see if that makes anything work as it may show a circuit break as the problem.
Sorry I can't be of more help.

follow the wiring wherit passes through from the hatch to body of vehicle sometimes they pinch or corode and break, this sounds like a broken wire to me,

Here are some things to check:-

1 The brake light switch
2 The fuse for the brake lights
3 The bulbs for the brake lights
4 The bulb contacts in the brake lights
5 The earth connections in the rear light clusters
6 Generally check for loose or broken wires in the vucinity of the brake light switch and the rear light clusters.

See if bulbs have burnt out in the left brake light and rear turn signal (one bulb if combined) and also rear center high mount brake light.

If the left turn signal has a slower speed than the right turn signal, this is a symptom of a bulb or bulbs burnt out.

Usually, the wiring is not a problem, but I would not rule wiring (or sockets) as a problem out.

Good luck on this repair.

go to the brake pedal siwtch and check voltage there, the center light is not on the same circuit

Brake light on top works tells me the switch at the pedal is ok. Turn signals working tells me that the turn signal filaments have power.

I would try changing the bulbs and if that doesn't work have an electrical shop trace the wires and check for power on the brake light circuit in the back.

Well, have you checked the fuse? Maybe stick another one (of the same size) in there anyway. If that's ok, then check the stop light switch. It'll be somewhere along the brake pedal linkage/ arm under the dash or under the hood around the linkage or master cylinder. Look around. You can short across the wires temporarily to see if they light up and then you'll know if that's it.

have you checked the earthing continuity-if it's this other bulbs may also partly light when brakes used
otherwise-
Check continuity of live from center to lh & rh lights and/or is there a live at those lights

check behind the brake peadle for a little button that pushes in and out when the peadle is pressed(this is your brake light switch) some cars have more than one of theese. manualy let the button out if the light works the switch is good if it does not disconect the harness from the switch and take a small piece of wire and jump the two prongs on the harness if the brake lights come on then you need a brake light switch. if this doesnt work check for power at the switch. if no power you have a bad fuse if there is power and you already jumped the wires to the switch then you have a broken wire between the switch and the tail lights.

Hello. Check relay RMI5 in REM unit located in left side rear of cargo area. As you look at it it's to the right of the central electrical connector 5th from bottom. Matt