I ordered two DIY pro kits (with the TVOC sensors) earlier this month and went to start working on them yesterday. After flashing the firmware, neither one would create a hotspot for me to connect to. Looking at them and doing some googling, i found they include knock-off Wemos D1 minis (labeled "mimi"). It looks like they're aware there are Wi-Fi issues, but the chips are still being used [0][1]. I sent in an email yesterday but I'm not expecting a response until at least tomorrow.
[0]: https://www.airgradient.com/open-airgradient/blog/d1-mimi/
[1]: https://forum.airgradient.com/t/issues-with-new-dyi-pro-pres...