Since the General Data Protection Regulations (GDPR) are since a few months actively being enforced, most WHOIS data regarding EU institutes or persons has been removed. Not sure about the how and why, but it seems that IANA simply was not ready for the new ruling and have not adapted their policies to the new rules.
Consequently, using WHOIS records for investigative purposes is almost pointless. Most tools out there do not have the data anymore. But there is good news.
A lot of WHOIS data can still be found in http://domainbigdata. Not sure about the backgrounds of this service, there is some complaints about privacy concerns, but this site may for the time being a good alternative. Give it a try and let me know please.