FYI the "bar" they refer to is just the graphic below the stats with health, attack, armor and then in the second column, resistances. I noticed in the actual stats listing above, after Patch 3 my shield-equipped characters had LESS front armor than they did normal armor... by the amount of the shield's value. Some of the non-crafted shields seemed to be giving NEGATIVE armor. How anything in patch 3 could have touched this, let alone break it, I dunno, but it is probably related to that bar "fix" they applied and clearly did not test thoroughly. Because the instant i logged into the game, all my shield toons had this issue.
For crafted shields, some player testers have reported that while the shield displays 0 value, and the Armor and Armor: Front ratings are the same, the damage mitigation of a shield seems to be unaffected.
I removed and re-equipped the neg-armor shields when I saw them, and that seems to have cleared the display, so I dunno if they were really giving neg armor or not.
I am not sure why crafted and non-crafted shields values would be calculated differently or send their values to the stats page differently, but there's a lot about this game's coding I wonder about.