I would like to ask, is the property management company fully responsible for the theft of my electric bicycle in the storage room after 12 am? .....

The stolen bicycle in the storage room belongs to the owner's exclusive area. No one else will be in charge of this matter except the insurance company. If you produce evidence to prove that the property management company has not fulfilled its safety management obligations in accordance with the management convention and sued the property management company, they will bear part of the responsibility.