I think many of you have gotten this to work, but what's the trick to getting it to show up?

Running 7.12.1 and now seeing the card, already playing with LTE mode, mbim and serial with no luck

This is not recent but may still apply.

From https://wiki.mikrotik.com/wiki/Cellular ... _modems_01

To make the EP06 modem working on most of the mini-pcie slots of the RouterBoard you need to tape the USB 3.0 pins on the modem or tape the PCIE pins on the mini-pcie slot as the USB3.0 pins are not compatible with the PCIE pins - modem will not be recognized in the board. Also some reports from the MikroTik users reports that a firmware upgrade is suggested to make the modem work more stable. Latest confirmed firmware version is EP06ELAR02A01M4G.

To make the EP06 modem working on most of the mini-pcie slots of the RouterBoard you need to tape the USB 3.0 pins on the modem or tape the PCIE pins on the mini-pcie slot as the USB3.0 pins are not compatible with the PCIE pins - modem will not be recognized in the board. Also some reports from the MikroTik users reports that a firmware upgrade is suggested to make the modem work more stable. Latest confirmed firmware version is EP06ELAR02A01M4G.

Yes and no. Taping is not necessary, modem can be forced into USB2.0-Mode via standard AT-Commands:

Firmware from EP06ELAR03A08M4G (rev.3.08) works in SXTR/LHGR (USB2.0 mPCIe bus) without tape/isolation USB3.0 pins. This fw have a new feature to disable USB3.0 by
AT+QUSBCFG="SS" <- query USB3.0 function
AT+QUSBCFG="SS",1 <- Enable the USB3.0 function

****** USE THIS SS,0 to allow card to go into older MT boards with 2.0 USB ******
AT+QUSBCFG="SS",0 <- Disable the USB3.0 function (This help us in RB with USB2.0 bus)

Latest available Firmware from official Quectel support is EP06ELAR04A06M4G from August 2022.

Running 7.12.1 and now seeing the card, already playing with LTE mode, mbim and serial with no luck

Did you put into the MBIM mode?
AT+QCFG="usbnet",2

How many "channels" are shown in /port/print (system>ports in winbox)?

Also if you have an APN set, you need to UNCHECK the "use-network-APN" option.