Column not not shown in visualize

Elastic Stack Kibana
1

I have some data with the following columns.
m_cvo_query_2

While I'm able to view them all in Discover, the column 'Position' does not appear as an option when I try to use it a field to visualize.
I have multiple files with similar data and this problem arises only with this set.
What could be the cause of this ? How do I solve this ?

Elasticsearch version - 7.7.1
Kibana version - 7.7.1

2

At first,you should refresh your index-pattern in the configure page.
And take a srceenshot of your index mapping.

3

The problem was that the data had some special characters in those columns. Removing these seemed to have solved the problem.
Thanks for your help.