I have a dialog list, and load a file (a log) with the /filter command, but the file is not complety loaded. If the file is short (5000 lines or less) the file was loaded completely. The problem is with files with 20000 lines or more. I think that is a byte limit, not a line limit because in one file I load always 24118 lines and other 32736.
Some kind of byte limit to dialog list?

Does the same problem happen with /loadbuf?

Yes with /loadbuf load the same lines

I made a file with 50,000 lines, each of 100 characters, and indeed only 32,736 lines were loaded to the list. Looks like a bug to me.

mIRC v6.14 @ Win98 with 128RAM