Why are all clients only connecting to one AP in my salon?

Hello all - new here.

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Last night I set up a UniFi network at my salon. I've got the USG, the POE switch and 3 Pro AC APs. Two of them are in my main, larger building (Pedicure AP, Manicure AP), with one next door in my smaller building (Wax AP). The Mani/Pedi APs are about 80 feet apart but are in two separate rooms with firewall (literal fire, not networking) between them. Ever since setup, I literally cannot get a device to connect to Manicure AP. I'm new to UniFi so it may be a silly question but I can really use some help. I tried dialing back the power of both APs from "High" to "Medium" based on a blog post I found but to no avail.

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Screenshot for reference: https://imgur.com/a/l0Fo9ss

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Any help is certainly appreciated!

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