Hi Andrei,
I am a colleague of Ziv and I will be the one providing support.
Thank you for providing the SOAP request and response logs privately. It seems that you haven't received Ziv's reply which he sent to your email address.
I tried to replicate the TargetingIdeaService call using the same TargetingIdeaSelector parameters on my test account, and I was able to receive a successful response on my end. Attached is a text file of my SOAP request and response logs. That said, could you retry your request once more? If the situation persists, you may send the updated SOAP request and response logs so that I can investigate further.
Regards,
Hiroyuki
Google Ads API Team