Zoho Desk. Custom field max multiline length Issue.

Zoho Desk. Custom field max multiline length Issue.

Hello. I have an issue with a Zoho Desk Custom field.
I created a custom multiline field. I tried to insert some text more than 5000 characters, and i got this error.

Insufficient Privileges to perform this operation. Contact your Administrator.

I tried different accounts. I got this error even with an owner`s account.

Can you help me please?