Hi all,
We managed to get around this issue by adding twitters updated ip range to our firewall rule on our web server. This could be the same issue for you guys, the full list of IPs we have allowed are as follows:
104.244.40.0/21, 185.45.5.0/22, 185.45.5.0/24, 185.45.5.33, 185.45.5.44, 192.133.76.0/22, 199.16.156.0/22, 199.59.148.0/22, 199.96.56.0/21
Hope this helps?