After you flashed the image to your sdcard. Remember to rename the wifi firmware "brcmfmac4335-sdio.bin" to "brcmfmac4335-sdio.transpeed,8k618-t.bin". Then copy both "brcmfmac4335-sdio.transpeed,8k618-t.bin" and "brcmfmac4335-sdio.txt" to /lib/firmware/brcm directory on your sdcard. I'll automate the process in future builds.
https://github.com/LibreELEC/brcmfmac_sdio-firmware/blob/master/brcmfmac4335-sdio.bin and https://github.com/LibreELEC/brcmfmac_sdio-firmware/blob/master/brcmfmac4335-sdio.txt
