The side road should have a warning sign.
That's the problem, should not must.
Should in TSM means that a missing sign can be queried and TBH, likely win if it were a case of driving a short way into a bus lane.
Would likely win here had OP parked, looked at the sign and left.
Could even win had OP parked and not seen the sign as it was turned.
But parked in a bus lane, take a photo of the sign (which shows they knew the time restrictions) and left the vehicle parked in contravention.
I hope I am wrong but can see Mr Chan shaking his head