Can not add subdomain when main domain contains 0

I found a strange bug, when my domain has 0 in name for example i0io, the first one is zero not O, I can not add subdomains to this domain:

Error message: Invalid domain.

Is there reason why?

Provider: Digital Ocean

System: Ubuntu 18.04

OLS or Enterprise?
OLS version 1.9 build 4E

Installing from official server or mirror server?
official

Install Memcached extension for PHP?
no

Install LiteSpeed Memcached?
yes

Install Memcached?
no

Install Redis extension for PHP?
yes

Install Redis?
yes

Thanks! It works after update

nice