Search export: custom fields with varchar > 255 get truncated

How to reproduce:

• create a custom field with Data Type "alphanumeric" and field type "checkbox". Create answer options such that the sum of the length of all their label fields is greater than 255 chars.
• create a contact select all the boxes for the field
• search -> export the contact or activity

Result: the data will be truncated to 255 chars, meaning that some of the later values in the list will be lost.