When using 2 shields by having the offhand shield held up when it breaks the main hand shied gets activated but does not block arrows.
You can replicate this by holding left click with the offhand shield active and holding another shield in your main hand and when your offhand shield breaks it will ignore the now equipped shield
Linked issues
duplicates 1
Attachments
Comments 2
Resolving as a duplicate of MC-168573.
Probably a duplicate of MC-168573. Thank you for the report though, the ticket was reopened.