As Lancair70 and LexAir have already pointed out, the answer would be an interpretation of CAR's 195 & 196 I reckon.
CAR 195 (1) At night and in conditions of poor visibility, the operator and the pilot in command of an aircraft must comply with the rules in this Part requiring lights to be displayed in relation to the aircraft.
CAR 196 (3) Unless CASA otherwise directs, an aeroplane in flight or operating on the manoeuvring area of a land aerodrome shall display, in addition to the navigation lights, an anti‑collision light consisting of a flashing red light visible in all directions within 30 degrees above and 30 degrees below the horizontal plane of the aeroplane.
If your reading of CAR195 is that you only need to display lights at night then flying during the day without an operational beacon would seem to be ok, unless you encounter poor visibility (how poor?) then it would apply again.
I would read from CAR 196 that because your aircraft already has a beacon fitted, then unless CASA exempts you, it has to be working, irrespective of whether you have strobes etc. fitted or not, whenever flight conditions dictate that you display the mandatory lighting.