Hello Sebastien
I will start by mentioning that my explanations (pictures) are on background different from what you have. This is because you migrated settings from previous AS versions, while my examples are on current templates. However, no need to worry, since the solutions are available regardless these configurations changes.
I guess that the model is in metric units and imperial bolts are used. Some properties are inherited from 3d model units (like in your situation).
Solution 1)
You can set to have the bolts "split" into bolts+washer+nuts on BOM template => you will get similar result with what you have for anchors.
However, not sure if you want to have the nut and washers too.

Solution 2)
Open Management Tools and set the following default as it is in the next picture (add syntax [20,5006,474] after percentage sign and before diameter).
This will change the units for all the bolts diameters when it comes to output documentation (details included). You need to recreate the BOM (including model extract) and update details to notice the changes. Also, please keep in mind that this setting will remain available for other projects too and most likely you will want to change it back.