Advice: went to walk a dog and there was no keys

I have this 1 walk a day for a week with a new client. They left a lock next to the building with the keys and fob. All good the first day, the lock was there and no problem. Second day (today) I go, there is no lock. I texted and called asking if they change the place of the lock, nothing. At this point I have to go to work, when they respond they tell me they'll see what happen. So I just left, I won't coming back for the day because I finish work almost 11 pm tonight, they know I'm just available for the morning. I just want to know if there is anything I should do to prevent any problems, I recorded a video of my searching the lock and s picture, started the Rover card and put that I couldn't access the apartment and finish it.

First time it happens, any advice is good. I'll be there tomorrow, hopefully doesn't happen again.

Edit: I texted today and they say no to come because there are not home until Saturday and there is nobody to open the door for me. At this point I'm worry about the dog.