Data missing for some symbols, was: Symbols Missing

I am sure this is not a new problem but can't find the right references to fix it. Using 6.30.5 and data from Premium Data. Problem = missing data for certain (? random) symbols. Ex =$NDX, CA ++. All seems well from Premium data side and have run Tools/Update US-- multiple times. Thought maybe Tools/Data Purify was what I remembered but this seems to just sit there with no progress when opened. Apologize in advance for probably basic question like this.

One thing to remember is that Tools->Update US symbols list is intended to be used with local database only.
If you are using data plugin driven database then all tasks are governed by the plugin.
Now you can have a mix of 'local' and 'external' symbols. Go to Symbol->Information window and see if those symbols with problems don't have "Use only local database for this symbol" flag turned on. It should be OFF if you want data from plugin.
More on this in the manual
http://www.amibroker.com/guide/h_workspace.html

@JWVee: For a PremiumData-based database, you should be running Tools->US-PremiumData rather than Tools->Update US symbol list and categories. This is due to Premium Data having much more extensive and complete symbol metadata. You never need to run Tools->Database Purify. Further documentation on the procedure is here: https://www.premiumdata.net/support/amibroker.php

I believe I have done all suggested. Each time I run Tools> US -PremiumData it hangs at Stage 3/7 at NYSE Arca...... and throws an error re Script... Line 1327, Char 4, Err 'undefined' is Null or not an object. Code 800A13F. It did complete once after numerous tries but never again, Now I do have 3 days of $NDX for instance on chart. Did reinstall integration several times also.

You are likely to get faster responses with regards to Premium Data if you write directly to Premium Data support support@premiumdata.net

@JWVee - please contact support@premiumdata.net for your Premium Data issue.