ACR X RWY INCURSION HAD NMAC WITH SMA MAKING GAR.

Narrative

AFTER HOLDING SHORT OF RWY 19L ON TXWY L; WE WERE CLRED BY TWR TO CROSS RWY 19L TO HOLD SHORT RWY 19R. AS WE CAME TO EDGE OF RWY 19L; WE SAW A LIGHT SINGLE ENG ACFT TURNING CLOSE-IN L BASE TO FINAL FOR 19L. WE STOPPED ABRUPTLY JUST SHORT OF RWY EDGE AND THE LIGHT PLANE EXECUTED A GAR. MOST OF THE TFC LNDG SNA WAS USING STRAIGHT-IN APCHS FROM A FEW MI OUT. I WOULD GUESS THAT THE GND CTLR WAS USED TO VISUALLY CLRING THE FINAL; BUT NOT LOOKING FOR CLOSE-IN BASE TFC. WHEN QUESTIONED ABOUT THE CLRNC; THE GND CTLR SAID THAT; THOUGH SHE CLRED US ACROSS; SHE QUICKLY SAW THE CONFLICTING TFC AND TOLD US TO HOLD SHORT. BUT; SHE SAID HER XMISSION WAS APPARENTLY BLOCKED. THERE WAS A GARBLED AND UNREADABLE XMISSION ON FREQ AT THAT TIME. SUPPLEMENTAL INFO FROM ACN 258288: WE STOPPED ABRUPTLY. DID NOT CROSS HOLD LINE. SMA MADE ABRUPT GAR. WHEN WE ASKED ATC TO EXPLAIN; CTLR SAID SHE HAD ISSUED IMMEDIATELY FOLLOWING OUR CLRNC TO CROSS; A CANCELED CROSS; HOLD SHORT CLRNC; WHICH WAS RADIO BLOCKED (I.E.; STEPPED ON) BY OTHER ACFT; AND WE HAD EVEN RPTED TO HER THAT HER XMIT WAS BLOCKED. WE NEVER RECEIVED OR ACKNOWLEDGED RECEIPT OF SECOND HOLD SHORT CLRNC.