How to regex through a json Response

Hej Community,

never had such a trouble extracting a dynamic value in LR. I'm disparing. 
I have a CRM System and want to extract a specific search result. The response is a json. But I need to regexp because there is a full html page in the "content"-part of the json response.

RAW Data:
Content-Type: application/json

{ ...
content: ... h1 class=\\"user-name\\">\\n <a href=\\"http:\\\/\\\/192.168.0.137\\\/task\\\/view\\\/29\\"
... }

Response Body:

{ ...
content: ... h1 class=\"user-name\">\n <a href=\"http:\/\/192.168.0.137\/task\/view\/29\"
...}

My Regex for the number in the URL looks like:

web_reg_save_param_regexp(
"ParamName=Number",
"RegExp=h1 class=\\"user-name(.*?)href(.*?)view\\\/(.*?)\\", => for Response Body 
"RegExp=h1 class=\\\\"user-name(.*?)href(.*?)view\\\\\\\/(.*?)\\\\", => for All (RAW)
"Group=3",
"Ordinal=3",
SEARCH_FILTERS,
LAST);


But it won't find a match. I checked it 100 times with: https://regex101.com/

Any help appreciated.

Thanks in advance and greetings from Berlin,
Stephan