Power KPI Matrix: Text Replacement for Current Value

I am using P. KPI Matrix to display Row based metric. Here is a summarization of my scenario:

1) I have a date filter to adjust window of Metric value

2) On certain days, some of the metric values are not available, so I want to replace those with a value in Text Replacement, such as "Not Available".

Although I am able to select individual columns from Format>Current Value and replace these values with a text, however as soon as I change the Date range on date filter, the replacement values are lost.

I was also trying to set the text value in the data set, but the metric values has to be numeric, so this isn't working. 

I am not sure if this is a feature where the text replacement will revert when chaning the date range on date filter. I also notice, it only happens when I change the lower date range but not the upper. On switching the lower date range to a value for which Text replacement was defined, the values are restored.

To summarize, I am looking for a way to set hard coded text string for certain metric values.