I have just set up a brand new localhost install of wordpress and Bricks. I have imported a JSON file of variables exported from another Bricks installation. All the variables are visible in the Bricks variables manager with their values and I can select the variables in element fields when I am setting up the theme styles:
OK, what I have just tried was manually creating a new variable and low and behold all the imported variables suddenly appeared on the front-end.
Surely you don’t need to manually create a variable before importing as that does not make sense.
Unfortunately, I cannot reproduce the issue (I tried it twice). Would you please test it again and document every single step so we can reproduce the problem if necessary?