Dear Iuri,
i could reproduce the problem of the form with RegisterRestrictEntireServerToRegisteredUsersFilters is activated, The problem seems to be like since since ages (at least 14 years+). When this parameter is set, a filter named "ad_restrict_entire_server_to_registered_users" is registered, which is pretty invasive and tries to do what auth::require_login does. This is at least my understanding. However, it just respects query variables, but ignores form variables.
Anyhow, I've replaced the magic redirect call with "auth::require_login", and now it seems to work fine. The modified function is now [2] . Iuri, please test as well.
Does anyone know, what packages uses "*/user_please_login.tcl"? This name/pattern is probably some legacy and should be removed.
-gn
[1] http://fisheye.openacs.org/changelog/OpenACS?cs=MAIN%3Agustafn%3A20190115183056
[2] https://openacs.org/api-doc/proc-view?source_p=1&proc=ad_restrict_entire_server_to_registered_users