From my interpretation of your base search - the issue is that the base search is not transforming. This is a requirement for post-processed searches
https://docs.splunk.com/Documentation/Splunk/8.0.3/Viz/Savedsearches#Post-process_searches_2
If you take a simple search with stats/chart command and then run it in the standard search window, you will get the results you want. However if you split this in a form/dashboard and only have the initial search in the base search, you will not get any results from your post processing. You will need to add a stats command or similar to the base search to generate a table of results before this will work.
If I take one of your examples, the full query is as follows
index=perfmon source="Perfmon:LogicalDisk" counter="% Free Space" | search host = DMOPWMD1PDDB0* | eval FreeSpace =100-( Value ) | stats min(FreeSpace) as hostavg by host,instance | table host,instance,hostavg | chart min(hostavg) by host,instance
It looks like you have created the following base search - however this only returns raw events and not an table
index=perfmon source="Perfmon:LogicalDisk" counter="% Free Space"
I would split this up as follows
Base search
index=perfmon source="Perfmon:LogicalDisk" counter="% Free Space" | eval FreeSpace =100-( Value ) | stats min(FreeSpace) as hostavg by host,instance
Post-processing search
|search host = DMOPWMD1PDDB0* |chart min(hostavg) by host,instance
In many cases, you need to create a temporary stats table in the base search, just to get this to work, even if you would not normally do this in an interactive search. If you base search cannot be easily combined into a single stats table, then you can create multiple base searches. I don't see the code you are using for the search ID's so just in case, it needs to be in this general format
<search id="BaseSearchName1">
<query>index=........</query>
<earliest>-24h</earliest>
<latest>now</latest>
</search>
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