Well one how long have you been dating? Are you exclusive? I know I asked a lot of questions before I answered but they do matter.
If you’re not dating exclusively even with a girlfriend title and you would be surprised how often that happens, it doesn’t matter because you’re not the one she claims. It’s usually a guy thing to do but it happens. She doesn’t want to show you off and is keeping her options open. To place a picture it would come off shady when her co- workers who know she’s playing the field inquire of who you are.
If you’re exclusive and it hasn’t been that long since you have made it exclusive then bring it up and see what her answer is. Maybe at work she wants to separate personal from private. Maybe she forgot and hasn’t gotten around to it. Speak up and make it known you would like a pic up of you or you and her together.
Do you have a picture up of her. I would assume yes since it makes no sense to require or ask for what you aren’t giving. I think this is a minor issue unless you suspect that she’s not faithful. If you do then you would need to explore that. However take it slow and deal with the issue at hand before you jump to conclusions. I do believe and hope it’s just a small infracture that can be easily worked out.
Remember there’s a difference between privacy and secrecy.
Good luck.