LX4 optics are hi-power, relative to DACs or SR4 and, at least in the case of the Mellanox SX60xx series of switch, are not well supported. I struggled for years to get one to work with my SX6018, hacking away at the firmware to no avail... then one day a good samaritan PM'd me a secret cli command to enable LX4 and I was off to the races.
Unless you need duplex LC/LC, I would recommend getting a cheap SR4 transceiver and a cheap OM4 MPT cable. Or, if your equipment is close enough and bend radii aren't an issue, just go with a DAC.