Some transfer agents have a blanket policy to not release SS information. Some have changed their policies between the times a company engaged them as their TA's and now suffer the consequences of the changed policy. Sometimes a company may make the effort to change TA's for this reason. Normally though, a company will update shareholders with quarterly and annual reporting.
In any case, a blocked TA is only a red flag for investors looking for information in that manner, not a red flag necessarily signaling any kind of issue with the stock or the company.