mongodb - Drupal 7 views block with default value contextual filter does not filter on page (Mongo) -

tl;dr: views block, contextual filter, default value. results show in preview, not on page. page = taxonomy term page path alias. running on mongo.

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how problem differs other contextual filter block issues i've seen:
- using mongo
- have default value set on contextual filter
- results show in views preview, not on page

using drupal 7 on mongo, efq views, need display nodes of nodetype have been tagged term term, on term page. (with drupal on mongo, taxonomy index stored in mysql node content in mongo, term pages don't work expected, , return no content. view necessary establish functionality. <-- yes, stupid.)

my taxonomy entity own fields, & tagged content appears in block, below terms own fields. (this why didn't make page view display tagged content -- bc. must display term's own fields.)

taxonomy term pages have path alias, "vocab/term-name".

configurations i've tried work in preview not on page:

1: using path alias.
global: null forarg(0)
node: tags arg(1)
when filter not available:
- provide default value: taxonomy term id url
- load default filter term page

or
-- raw value url, path component 2
-- "use path alias" checked

when filter available:
- validator: taxonomy term, vocab tags
- filter value type: term name converted term id
- transform dashes in url spaces in term name filter values

2: use term id
when filter not available:
-- raw value url, path component 3

when filter available:
- validator: taxonomy term, vocab tags
- filter value type: term id

view results in preview appear correctly whether using term name or term id in c.filter. no matter how it's set, block on actual page returns nodetype nodes.

on taxonomy page, block displayed in custom region, or in main content area of page. in both cases, nodes display, unfiltered. ajax enabled on block, measure.

topics i've read / tried don't apply / don't work: (can post 2, have 15):
drupal 7 views contextual filters page & blocks
drupal 7 views block , contextual filter not working

turns out settings worked were:

contextual filter: taxonomy tags default value: raw value url, path component 2  check "use path alias" when filter present - specify validation criteria validator: taxonomy term (from checked vocab) filter value type: "term name converted term id" check "transform dashes in url spaces in term name filter values" 

the global nulls arg(0) in way. without that, using value arg(1), things work fine.