macbook pro 13 2018 only left side Thunderbolt 3 ports charge

The charging cord that comes with the Mac—is just that power, data transfer would be severely hobbled.

USB-C Charge Cable (2 m) - Apple

About the Apple Thunderbolt 3 (USB-C) Cable - Apple Support

Port power

2018 models ship with Intel's eighth-generation Core i5 or Core i7 processors, which both support up to 16 PCI Express lanes, providing enough bandwidth for maximum data transfer speeds up to 40Gb/s on all four Thunderbolt 3 ports.

2016 and 2017 models of the 13-inch MacBook Pro with Touch Bar could be configured with sixth- and seventh-generation Intel Core i5 and Core i7 processors, which supported up to 12 PCI Express lanes, limiting full speeds to the two left-side Thunderbolt 3 ports, with reduced bandwidth on the right-side ports.

Now, users have the freedom to plug higher-performance peripherals into any Thunderbolt 3 port they desire without compromise.

All three generations of the 15-inch MacBook Pro with Touch Bar have always had four full-speed Thunderbolt 3 ports, while the 13-inch MacBook Pro with function keys has only two Thunderbolt 3 ports, both full speed.

ref: https://www.macrumors.com/2018/07/19/2018-13-in-rmbp-touch-bar-full-speed-thunderbolt-3/

more here—

The name USB-C refers ONLY to the connectors, It does NOT uniquely identify the cable.

Many different cable have at least one USB-C connector, and they all have different capabilities.

The cable Apple ships in the box for charging has only charging and USB-2 (think keyboards) capabilities. It can not POSSIBLY run a display of any description.

https://discussions.apple.com/thread/250215716

JekCo wrote:

MacBook Pro (13-inch, 2018, Four Thunderbolt 3 Ports)

Thanks.

You can try both :

resetting NVRAM/PRAM http://support.apple.com/kb/ht1379

resetting the  SMC  https://support.apple.com/en-us/HT201295

You can try running the Diagnostic/AHT  http://support.apple.com/kb/HT1509 

not definitive by any means, but may kick out an error code.

In or out of warranty you can get a free over the counter 'Apple Service Diagnostics' test /assessment

Make an appointment for a "hardware issue"—

https://www.apple.com/retail/geniusbar/

I am using the supplied charger and cable. Plugged into either the left side ports it charges battery fine, but when plugged into a right side port neither will charge the battery.

Opposite for data, when using a usb 3.0 thumb drive with a usb C adapter right side ports xfer data but left do not.

What does it say in >About This Mac

Can you verify your "2018" (?)

Have you tried different set of cables/USBdrive to test (?)

2016 and 2017 models of the 13-inch MacBook Pro with Touch Bar, limiting full speeds to the two left-side Thunderbolt 3 ports, with reduced bandwidth on the right-side ports.

I can go on to say— port definition is redefined with each reboot or you can

Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379