All of this hassle with breakers is why one should investigate BlueSea ABYC compliant fuse panels and the ABYC E-11 to determine the correct fuse size.
My 30 year old boat came with breakers, and not knowing whether the device or the breaker was faulty doubled the troubleshooting complexity and replacing breakers is much more expensive than fuses.
Of course someone (like the mechanic in the marina I'm at) will say fuses are not ABYC approved, so if someone makes that case, please quote the ABYC section, and explain why Blue Sea sells ABYC compliant fuse panels and fuses.
Hey! Want to buy a box of used breakers cheap?