Increase the size of ltspice error log file contents
The error log has no settings, but a simpe test of a (simple circuit) .step of 10000 (1e4) values with .meas shows everything in the log, it just took a while to open it up. Maybe you have to wait for the log to be fully loaded. It is possible to press Ctrl+L and display the log while it is still being read, resulting in an incomplete log (at least I remember it possible once). In that case, you have to close the log and reopen it, it doesn't refresh while it's opened.
It can also happen that it looks like you can't grab the scrollbar and go to the bottom of the log (for very large files), but if you click in the log and then navigate with PgUp or PgDn, it works.
Or simply open it up with your favourite text editor from the disk. Unless you set the path for storing .raw files in the Control Panel, it should be right next to your schematic. But, personally, I have never seen the error log to be truncated in any way.