Yes, the Lexar Professional 1667x 64GB SD is compatible with the Sony FX30.
Lexar Professional 1667x is an SDXC V60 card. It meets the FX30's SD floor for XAVC HS/S 4K (V60 or higher) but not the V90 required for XAVC S-I 4K, so it works for standard 4K only.
Limitation
Records XAVC HS/S 4K (280Mbps tier, the FX30's SD floor for that mode is V60, which this card meets). Cannot record XAVC S-I 4K (600Mbps), which the FX30 requires a V90 SD card for.
“XAVC HS 4K 280Mbps CFexpress Type A memory card (VPG200 or higher) SDXC V60 or higher”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)