SL3 odd behaviour today

[Carrot]

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Got my SL3 on launch day, and used an SL2-S for a year before that, so I’m relatively well versed in their operation. Shortly after getting the SL3 a firmware update was released, which I actioned with no lens attached via the SD card route. I then attached each SL APO lens (28, 35, 50, 75, 90) to see if there were any firmware updates for them, but none appeared, and the camera indicated they were all on v4.0, just as they were beforehand. Over the past few weeks I’ve used the camera with my SL and M lenses with no issues.
Today using the SL APO 50mm again, the camera unexpectedly displayed a message to say lens firmware was updating. This ran for several minutes and then the camera died. I removed the lens and it took a few goes of removing and replacing the battery to bring it back to life. The 50mm is working fine, but still shows firmware v4.0, so presumably no update took place. I’ve no idea why this happened, and it can’t be a Fotos app issue as I’ve never downloaded that to my phone.