Training with Yergius can grant training dice "increases" that seemingly do nothing
Theoretical training with Yergius can yield non-increase increases like 1d3 to 1d3 or 4d5 to 4d5.
Problem
Theoretical training with Yergius can yield non-increase increases like "You improve the modifier in your 'Climbing' skill from +1d3 to +1d3." under certain circumstances.
How to reproduce it
Usually I can get this to happen by advancing the skills Yergius can train (e.g. Stealth) via level ups, until the training dice is 1d3. Then I go to him and ask for theoretical training on that skill. The first payment will "increase" it from 1d3 to 1d3. Further training rises it to 1d5, 2d4, etc.
This also happens when your training dice are at the maximum value, which I believe is 4d5. Attempting to train such a skill with Yergius at that point will result in further "increases" to 4d5.
Notes
This may be related to the following (code-dived):
"First is your skill advancement schedule. This corresponds loosely to your increase dice, however, it extends in both directions. You could have an advanchement schedule of 1 level beyond 4d5; this would result in 4d5, but the next time your dice decrease, it would stay 4d5. In the other direction, your advancement schedule can be smaller than the class-dependant minimum dice; if this is the case, increases to the dice will appear to do nothing."