Web Preview only working on one domain?

[MiniBlueDragon]

I have several different domains on my Parallels Plesk Panel v10.4.4_build1013111102.18 os_CentOS 6 on Linux 2.6.18-028stab099.3VMS, however despite having the same DNS settings on them only one of them (the most recent one added) has a working 'preview' when clicking the preview icon under Websites & Domains.

Main Domain = maindomain.com - Actual domain works fine and is live. Preview is broken.
Preview Domain = previewdomain.com - Actual domain works fine and is live. Preview is broken.
Working Preview Site = workingpreview.com - Actual domain works fine and is live. Preview is working.
Broken Preview Site = brokenpreview.com - Actual domain works fine and is live. Preview is broken.

If I take the working one and a similar one, both have the same WordPress files installed and both have a correct database set up. Both have similar DNS settings:

WORKING Preview resolves to - http://workingpreview.com.188-121-63-239.previewdomain.com/

*.webmail.workingpreview.com. CNAME workingpreview.com.
188.121.63.239 / 24 PTR workingpreview.com.
ftp.workingpreview.com. CNAME workingpreview.com.
ipv4.workingpreview.com. A 188.121.63.239
mail.workingpreview.com. A 188.121.63.239
workingpreview.com. NS ns1.maindomain.com.
workingpreview.com. NS ns2.maindomain.com.
workingpreview.com. A 188.121.63.239
workingpreview.com. MX (10) mail.workingpreview.com.
workingpreview.com. TXT v=spf1 +a +mx -all
webmail.workingpreview.com. A 188.121.63.239
www.workingpreview.com. A 188.121.63.239

BROKEN Preview resolves to - http://brokenpreview.com.188-121-63-239.previewdomain.com/

*.webmail.brokenpreview.com. CNAME brokenpreview.com.
188.121.63.239 / 24 PTR brokenpreview.com.
ftp.brokenpreview.com. CNAME brokenpreview.com.
ipv4.brokenpreview.com. A 188.121.63.239
mail.brokenpreview.com. A 188.121.63.239
brokenpreview.com. NS ns1.maindomain.com.
brokenpreview.com. NS ns2.maindomain.com.
brokenpreview.com. A 188.121.63.239
brokenpreview.com. MX (10) mail.brokenpreview.com.
brokenpreview.com. TXT v=spf1 +a +mx -all
webmail.brokenpreview.com. A 188.121.63.239
www.brokenpreview.com. A 188.121.63.239

Does anyone have any idea what's likely to be wrong with my setup? GoDaddy were useless when I consulted them.