I just installed a Google Tag Manager WP plugin, https://duracelltomi.com/ and this causes the quform contact form the fail on submission. In Chrome it just hangs. In firefox, the screen goes blank and eeks out a send.
This tag manager plugin is popular so it would help to know if anyone has run into this and f there is a fix. I have contacted the GTM plugin creator and he is baffled. But it is definitely caused when the GTM plugin is activated.