Remote PHP via vagrant: Cannot parse configuration file

I'm trying to set up remote php on my vagrant box and running into a few issues.  I'm running CentOS Linux release 7.3.1611 (Core) with PHP 5.6.5 from the SCL repository.

1) When I try to ssh via Tools > Start SSH Session  and I select my vagrantfile, nothing at all happens. Is there some way I can see why it's silently failing?  If I select Edit Credentials... instead and specify the user/pass, it works.

2) When I try to set up remote PHP, I have to specify SSH Credentials, because the Vagrant option doesn't work (I'm assuming this is related to #1, above). For PHP executable, I'm using /opt/rh/rh-php56/root/usr/bin/php, which is the correct path, but I'm getting the following:

PHP works fine on the vagrant host. I can run php -i and get valid phpinfo output, including xdebug extensions, etc.

Any clues for troubleshooting this?