There's been no real investigation on the stained bedding and kids' chairs in secret tunnels under NYC synagogues.

Question

Under New York synagogues, a year-old discovery remains unaddressed. Stained bedding and children’s chairs in secret tunnels—no real investigation, no accountability. Why does this network of shadows continue operating in plain sight? The same group that spent decades hiding "like mice" now weapo...

Answer 1

From what I found this claim is false and the video that was posted was misguiding. The people who invaded the tunnel were a mix of people trying to stop construction and blockage happening. Some others tried to also go in with the people defending the passageway, which is where the video sprouted and became a misleading post.

 I found an article on Newsweek.com that states, this was video was filmed by a group who unlawfully entered and damaged the building walls. It says Jonathan Greenblatt, who is the director of Anti-Defamation League, stated that this was false comparisons to the truth, saying there was involvement in human trafficking. 

Synagogue Secret Tunnel Mattress Prompts Frenzied Speculation - Newsweek

In another news article on APnews also says that it was mentioned this tunnel connected to a local children's museum which is false. The tunnel was said to connect to a synagogue. These were made for Jews within the Chabad movement and received thousands of visitors every year. There is no evidence supporting the claim of sex trafficking. 

Secret tunnel's discovery under New York synagogue spurs conspiracy theories | AP News
  Both authors for these articles are news representatives based in New York. 

This video was taken out of context and there is evidence supporting that. These tunnels weren't made to be used for any negative purposes. 

Comments

The claim that "These tunnels weren't made to be used for any negative purposes." cannot be verified as the tunnels were not an authorized construction and instead were illegally built by community members. Though there is no evidence that they were used for trafficking, we have very little information on who built the tunnel or why. According to the BBC "It is unclear who built the tunnel, how they did it and what their motivations were." With the information we have available at this time, there is no way of saying what purpose the tunnel was or was not built for. In fact the source you linked from AP News claimed that "Rabbi Motti Seligson, a spokesperson for Chabad, said the underground passage was built by a group of “young agitators” seeking unauthorized access to the synagogue." If this is true, then a group of agitators seeking unauthorized access to a private space could be viewed as a negative purpose.

Sources:
https://www.bbc.com/news/world-us-canada-67947334
https://apnews.com/article/tunnels-new-york-jewish-synagogue-arrests-770-e133a0d771b61e1cc86b015157e5f78b

Answer 2

When looking into this claim, most of the information about stained bedding and kids chairs came from posts on social media, not any verified sources. Most of these post didn't even include evidence or any sources at all, which really makes me question the reliability of them.

To find better information, I checked reporting from the Associated Press, which covered this incident. According to them, the tunnel was real, but build illegally by a small group who wanted to expand the synagogue. Police were involved, arrests were made, and he city even explored for safety issues. Through all of this, they did note that many of the claimants about this tunnel being spread online were unsupported and false. https://apnews.com/article/synagogue-tunnel-fact-check-30dea243e1619716f8274ebc7f596f5c?utm

To conclude, this claim is misleading. There was an investigation into the tunnels themselves, but there is n credible evidence that authorities ignored or failed to investigate "stained bedding" and "kids chairs". Those details come from social media speculation rather than real sources.