It might also be worth checking the results of DBCC OPENTRAN in your problematic database.

Also, have a look at the results of

SELECT log_reuse_desc...

Am I reading your backup / maintenance schedules correctly?  You're only doing TLog backups during the work day, and not during database maintenance routines, such as index rebuilds?

Indexes...

What edition / version of SQL Server is the target?

If it's SQL 2014 or SQL 2016 RTM Standard Edition, you won't be able to continue, as those don't...

Alternatively, if you've got your list in Excel, it's presumably sorted in the order you want?

In which case, why not just build the ALTER LOGIN statements in a...

You're suffering from "Lazy Log Truncation".  It got me last month too...  The article linked is a Microsoft PFE report / note about what's going on, with pictures...

This sounds like the sort of thing that David Bird went through as the core of his SQL Overview system.  There's a series of articles - the first...

Is it actually a table, or is it an alias for a table elsewhere on the server?

do you see any error messages when you try to query the...