This is a common conundrum that relatively fresh designers find themselves in and has been discussed many times on the forums.
I suggest to do a little bit of digging in the employment forum.
As a general note, I’d say that showing work that is not in the public domain is risky.
Not just because your current employer would not like it if he/she found out and you are most likely legally prohibited to do so but also because it might make your interviewer think twice about how you handle confidential information.
As with most things in life, it’s all about the right balance. If you feel comfortable with showing the concept work because it is already a few years old or it’s not a direct competitor, go for it but be prepared that you might get questions if this has been cleared with your current employer.
I’d say that if you have a couple projects that are fleshed out and show your approach to design and skill set, it’s ok to just talk about other things you worked on without showing any protected images.
Design is about more than just hot sketches, modelmaking and hero shots. You can talk about your approach and strategy on how you tackle a brief and move throw the different stages without having to specifically point to a process board.
When interviewing designers, I always find talking about design philosophy and approach just as valuable as seeing hot skills, as long as there are a few examples that show that those are there too.
Best of luck!