Bard incurs arcane spell failure while wearing light armor

[Dillydally]

Hi, I noticed that my lv 5 half-elf bard Dwilbreth Du'andei triggered arcane spell failure while trying to cast Magic Weapon today. According to wiki this shouldn't happen if I have nothing heavier than light armor.
Here's a screenshot of it, in case it contains anything relevant:
https://imgur.com/xDWI7D3
The armour is Squad Leader's Boiled Leathers and this happened in Glumdrum Hall.

[Mia]

Maybe this is because your studded leather armour has +1 armour class, and is thus recognized by the system as a +4?  (Vagabond has a similar bug)

[Pigadig]

Mu understanding was that this change was added as part of the overall changes to Contriver sorcerers.

As such, when the change was reverted for Contrivers due to bugs, so too was the bard one as far as I know. Dil can chime in if it is otherwise.

[Dillydally]

Mu understanding was that this change was added as part of the overall changes to Contriver sorcerers.

As such, when the change was reverted for Contrivers due to bugs, so too was the bard one as far as I know. Dil can chime in if it is otherwise.

I have no idea how it was before the contriver update reversion. I joined the server on May 1st and spent the first few days bumbling around and trying to get a sense of the game mechanics in general. It's possible that the issue existed before, but I experienced it recently.