Yes and exactly as described by OP. Logging in, in both Firefox 54 or chromium-browser 60.0.3112.78 with ‘Use less traffic’ ticked, only 'All articles, Fresh articles, … Shared articles appear. Only after clicking on an UNREAD article do the unread Categories appear.
My server setup is on a physical machine w/ ubuntu server 16.04.x, apache2, php 7, postgresql, Tiny Tiny RSS v17.4 (ab8daa0) .
Firefox and chromium-browser on Linux Mint 18.2 MATE 64-bit.