Please hit me up from your licensed email to my csvreader email address for an update to v5.31.
I have the library back able to handle bigger Xlsx files. There's still going to be a limit, but it's now back to only needing to store the original 300mb in a single stream in memory, as opposed to the full decompressed 3gb.
I looked back at each of the sets of changes between v5.24 and v5.30, and found that for v5.28 I swapped out some zip file functionality so that it would work under .Net Standard compatibility. In the process I changed some of how the streams were being worked with in memory to get it to work at the time. In reworking it now, I was able to be a little more creative and find a different path that works and retains the original capability.
Bruce Dunwiddie