I too am experiencing a truncated standard output for task "Read File".
I'm on version 6.2.2, but see nothing in the release notes about this to suggest upgrade.
I realize this is a very old post, but it was the most relevant I could find. Obviously, the "Server Settings" has been drastrically overhauled since, because there is no longer a feature to turn off LimitOutput there. I do, however, see a LimitOutput xml setting in the server_settings.xml file, but modifying this in the XML seems to do nothing. Ironically, the documentation still points me to "Server Settings" and states that Standard Ouput is truncated by default and must be turned off in Server Settings. This should really be updated.
I've tried turning off all limits in the "Database settings" area of "Server Settings", but this too does not resolve truncation of standard output of "Read File".
I must be missing something, because a truncated "Read File" task to 2000 characters seems to be rather useless in most scenarios. Please help - I'm very close to just writing a .NET console app for this and being done with VisualCron, because I would have spent far less time at this point than digging through documentation and posting on this forum!