Issue with 2014 Crosstrek Camshaft and Crankshaft Position Sensors

On Monday morning, my 2014 Subaru Crosstrek 2.0i Limited (non-Hyrid) was very difficult to start. Turned the ignition on, cranked for a minute or so, then turned ignition off ... repeated this many times. Engine finally started. Check engine light on, cruise control light also on and could not be turned off. Three Diagnostic Trouble Codes, namely,

• P0340 (Camshaft Position Sensor A Circuit Bank 1)
• P0345 Camshaft Position Sensor A Circuit Bank 2, and
• P0335 Crankshaft Position Sensor A Circuit).

Because the intake, upper cylinder bank, sensor was easiest to reach, started Service Manual Engine Diagnostic Procedures for P0340. Step 1, check power supply of camshaft position sensor, OK. Step 2, check harness between ECM and camshaft position sensor connector, both ECM and sensor connectors OK. Step 3, check harness resistance between sensor connector and engine ground, OK. Step 4, check voltage between sensor connector and engine ground OK. Step 5, check condition of sensor, OK. Step 6, check camshaft sensor waveform, did not perform because I do not have an oscilloscope. Assumed the problem was with the camshaft position sensor. Removed it, noticed some oil gunk on it, cleaned it off, and reinstalled it while waiting for new part.
Next followed Diagnostic Procedures for P0345. Step 1, check power supply of camshaft position sensor, OK. Step 2, check harness between ECM and camshaft position sensor connector, ECM (B137 No. 30) and sensor connector (E35 No. 3) OK but ECM (B137 No. 16) and sensor connector (E35 No. 2) failed by having unlimited resistance. Step 3, check harness resistance between sensor connector (E35 No. 2) and engine ground, failed with resistance of only 3.5k ohms instead of more than 1M ohms. Step 4, check voltage between sensor connector (E35 No. 2) and engine ground, failed having 0 volts. Because I thought I might be dealing with an open/short circuit somewhere, went ahead removed sensor, cleaned it, and reinstalled it.
Did not yet undertake diagnostic procedures for P0335. Decided first to drive the car, clear the codes, then drive the car again and read the codes again. Much to my surprise, the car started with only 3 on/off cycles of the ignition switch. When I drove the car, the check engine light was off. I read the DTCs and no codes were in the memory. Car continues to start and drive OK.
Can anyone explain this situation?
From my google search, this seemed to be the only relevant Subaru Crosstrek forum covering DIY repairs. Does anyone know of any others?
Many thanks in advance for your help.