Price not displaying for some customers

Hi all,
Over the years I've had a handful of customers ask how much 'item x' is.
I assumed they just weren't looking hard or were on a mobile phone.
However, I've now had the chance to confirm it's not showing for them.

Unfortunately I don't know if it's a particular browser or blocker.

I do have text in front of my displayed price. Perhaps that is causing issues?

This bit of code is what inserts the text (incl/templates/yourtemplate/templates/tpl_product_info_display.php)
PHP Code:

  echo $one_time . ((zen_has_product_attributes_values((int)$_GET['products_id']) and $flag_show_product_info_starting_at == 1) ? TEXT_BASE_PRICE : '') . 'Hire ' . zen_get_products_display_price((int)$_GET['products_id']);  

Anyone encountered missing price before? I've never spotted it when testing in all browsers.