MacBook air immediately shuts down when power is unplugged

My Macbook air immediately shuts down when the power is unplugged, sometimes (much less often) it will last 10-12 seconds after unplugged before shutting down. I recently had the battery replaced 4 months ago. When the battery was replaced it would initially go for hours on a full charge. About 2 months ago it started having this problem of turning off immediately when unplugged.

So far I have

• Reset the SMC
• Reset the PRAM

My battery shows as 100% charged.

I described both my coconut battery results and information from my system report below. It is strange that coconut battery shows at 100% and by charger light is green but, with the charger plugged in, my system report shows it is not charging and is not fully charged.

I can't figure out how to paste in images of my system report or coconut battery, but if there is a way please let me know.

Coconut battery:

• Current charge: 6817 mAh
• Full capacity charge: 6817mAh
• Manufacture date: 2017-10-17
• Cycle count: 64

System report:

• Charge information
• * charge remaining: 6817 mAh
• * Fully charged: No
• * Charging: No
• Health information
• * Cycle count: 64
• * Condition: Normal
• Battery installed: Yes
• AC charger information
• * Connected: Yes
• * Charging: No

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