That's exactly why I am beginning to use BD DL discs.
So, I am having to re-index my entire database (long story) and was grabbing data from the BD discs again. So far of the 134 discs I have BD073 and BD080 had two and three titles, respectively, that reading stopped at, so I had to replace just those titles by acquiring them again. This is exactly why I'm using BD as my storage, so I don't face another HDD crash where I lose hundreds of titles at a time. I'm still considering to buy some HDDs to throw them on as well and use the BD discs as just the backups of everything, but, haven't done that yet after all these years.
Can anyone answer this? On each disc, say, 24 titles. Titles 1-12 I was able to read info from but it would crash at reading title 13 and 14, but, I could read info from titles 15-24. Later, to recreate the disc I had to acquire titles 13 and 14 again, copy titles 1-12 and 15-24 to HDD and then burn them all again to recreate BD073. How is it possible for a disc to be readable up to a point and then again after a certain point on the disc? I guess I always thought if a disc couldn't be read, it was dead.