No matter which one I activate, it always comes up blank

I did visit your site and what you have is a modrewrite/htaccess issue. Either your htaccess file is screwed up, your server misconfigured for this or you did not set the backend option for modrewrite.

Try yourself. This none modrewrite link works:
http://fotosbyerika.com/index.php?album=people&image=fitness_class.jpg
while the modrewrite one does come up with the blank page:
http://fotosbyerika.com/people/fitness_class.jpg.php

For sure this has nothing to do with the Wordpress import as you initially suspected.

htaccess file version 1.2.8.0;

When Zenphoto requires changes to the rewrite rules:

First make a copy of this file as 'oldhtaccess' in the zp-core folder so setup can test for unmodified files

Update the above and the define in setup.php

RewriteEngine On

RewriteBase /

RewriteRule ^admin/?$ zp-core/admin.php [R,L]

RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^albums/?(.+/?)?$ $1 [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [L]

RewriteRule index.php$ index.php [L,QSA]
RewriteRule ^page/([0-9]+)/?$ index.php?page=$1 [L,QSA]
RewriteRule ^page/([A-Za-z0-9-]+)/?$ index.php?p=$1 [L,QSA]
RewriteRule ^page/([A-Za-z0-9-]+)/([0-9]+)/?$ index.php?p=$1&page=$2 [L,QSA]
RewriteRule ^(.)/page/([0-9]+)/?$ index.php?album=$1&page=$2 [L,QSA]
RewriteRule ^(.)/page/([A-Za-z0-9_-]+)/?$ index.php?album=$1&p=$2 [L,QSA]

Rewrite rule addition for search

RewriteRule ^page/search/fields([0-9]+)/(.)/([0-9]+)/?$ index.php?p=search&searchfields=$1&words=$2&page=$3 [L,QSA]
RewriteRule ^page/search/fields([0-9]+)/(.)/?$ index.php?p=search&searchfields=$1&words=$2 [L,QSA]
RewriteRule ^page/search/archive/(.)/([0-9]+)/?$ index.php?p=search&date=$1&page=$2 [L,QSA]
RewriteRule ^page/search/archive/(.)/?$ index.php?p=search&date=$1 [L,QSA]
RewriteRule ^page/search/tags/(.)/([0-9]+)/?$ index.php?p=search&searchfields=tags&words=$1&page=$2 [L,QSA]
RewriteRule ^page/search/tags/(.)/?$ index.php?p=search&searchfields=tags&words=$1 [L,QSA]
RewriteRule ^page/search/(.)/([0-9]+)/?$ index.php?p=search&words=$1&page=$2 [L,QSA]
RewriteRule ^page/search/(.)/?$ index.php?p=search&words=$1 [L,QSA]

Rewrite additions for zenpage

RewriteRule ^pages/?$      index.php?p=pages [L,QSA]

RewriteRule ^pages/(.)/?$ index.php?p=pages&title=$1 [L,QSA]
RewriteRule ^news/?$ index.php?p=news [L,QSA]
RewriteRule ^news/([0-9]+)/?$ index.php?p=news&page=$1 [L,QSA]
RewriteRule ^news/category/(.)/([0-9]+)/?$ index.php?p=news&category=$1&page=$2 [L,QSA]
RewriteRule ^news/category/(.)/?$ index.php?p=news&category=$1 [L,QSA]
RewriteRule ^news/archive/(.)/([0-9]+)/?$ index.php?p=news&date=$1&page=$2 [L,QSA]
RewriteRule ^news/archive/(.)/?$ index.php?p=news&date=$1 [L,QSA]
RewriteRule ^news/(.)/?$ index.php?p=news&title=$1 [L,QSA]

RewriteRule ^(.)/image/(thumb|[0-9]{1,4})/([^/\]+)$ zp-core/i.php?a=$1&i=$3&s=$2 [L,QSA]
RewriteRule ^(.)/image/([^/\]+)$ zp-core/i.php?a=$1&i=$2 [L,QSA]
RewriteRule ^(.*)/album/(thumb|[0-9]{1,4})/([^/\]+)$ zp-core/i.php?a=$1&i=$3&s=$2&album=true [L,QSA]

Catch-all - everything else gets handled in PHP for compatibility.

RewriteRule ^(.*)/?$ index.php?album=$1 [L,QSA]

BTW, I tried both and they both come up blank.

I can access even modrewrite image page links if I call them directly but not with next/prev.

Please disable the static_html_cache plugin, might be that you see the issue of a bug recently reported and already corrected in the nightly, that only did affect a few servers.

Yes, indeed, that was it.