Firstly I'm reasonably sure the Shock Dampening Defense passive is not working properly as it doesn't seem to be giving benefit to all characters.  It is possible that the 1%DR suppression passives are buggy too.

Secondly there seems to be a weird 2-3% damage reduction penalty to my assassins and Tech Priests.  Entirely unequipped, these characters usually show 0% DR, but equipping gear does not seem to be giving the full benefit, leaving it overall 2-3% short, potentially more with buggy passives.

Example 1 - Character Broken: Level 93 Infiltrator Assassin, Skeletal Padding Defensive and 3x1%DR Suppression passives assigned.  No gear, DR is 0%. Should probably be 3% from Suppression Passives. Adding a Main Implant with 7.1% DR, gives a total DR of 5%.  Adding a Purity Seal with 11% DR gives a total of 16%.  Adding Armour with 41% DR (25+11+5 from Skeletal Padding) gives 56%.  Depending on rounding this is either 2 or 3% short of where it should be, or 5-6% if the suppression passives are not working.

Example 2 - Character Broken: Level 94 Dominus Tech Priest, Skeletal Padding and Shock Dampening Passives.  No Gear DR is 0%.  Should probably be 2% from Shock Dampening.  Adding 56% DR Armour (33 Base + 17 affixes + 6 Skeletal Padding) gives 54% DR.  Adding instead a 7% DR Main Implant gives 4% DR.  Adding instead a 10% Purity Seal gives 7% DR.  Seems to be a 2-3% underlying penalty and only the Skeletal Padding passive is working.

Example 3 - Character a bit broken: Level 97 Empyeanist Psyker, Skeletal Padding, Shock Dampening and 3x1%DR Suppression Passives.  No gear DR is 0%.  Should probably be 5% from passives.  Adding 7% Main Implant gives DR of 7%.  Adding 10% Purity Seal gives total 18%.  Adding 34% Armour (19+11+4 from Skeletal Padding) gives a total of 52%.  Items appear to be adding properly but passive Shock Dampening missing along with probably the Suppression passives unless they only show in mission.

Example 4 - Character not broken?: Level 97 Tactical Crusader, Shock Dampening and Skeletal Padding Passives and 3x1%DR Suppression Passives assigned.  No gear DR is 8%.  Should probably be 5% if Suppression passives and Shock Dampening were counting, otherwise 0%.  7% DR Main Implant Added which also pushes Toughness to 25 for extra 10% DR (so effective +17% for this item).  New Total 22%.  This is actually what I would expect it to be, but is not 17+8.  Adding an 11% purity seal pushes it up 11 to 33% which also seems ok (22+11), and Armour takes it over the cap.  Setting aside the initial wrong 8% number, the DR on this character does seem to add up from items and passives.