Email Notification for New Customer Order not being received

I’m having a problem where sometimes we receive a New Order email, and sometimes we don’t. Using PayPal Standard to process orders. I don’t see a pattern for what might be causing the issue. WooCommerce Orders are all listed as On Hold; I just added IPN to PayPal account because I thought that the issue might be related to the order status, but nothing has changed: all orders (including test order we just did) remain listed as ‘On Hold’ and we still aren’t seeing the New Customer Order email. All WooCommerce>>Settings>>Emails seem correct as does the PayPal settings. I don’t understand why sometimes it works and sometimes it doesn’t….any suggestions are very welcome, as I’ve been trying to fix for months now.

System Status Report:

### WordPress Environment ###

Home URL: http://www.pmcs-icap.com
Site URL: http://www.pmcs-icap.com
WC Version: 2.6.14
Log Directory Writable: ✔
WP Version: 4.7.2
WP Multisite: –
WP Memory Limit: 256 MB
WP Debug Mode: –
WP Cron: ✔
Language: en_US

### Server Environment ###

Server Info: Apache
PHP Version: 5.6.29
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PHP Time Limit: 30
PHP Max Input Vars: 1000
cURL Version: 7.24.0
OpenSSL/1.0.0

SUHOSIN Installed: –
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### Database ###

WC Database Version: 2.6.14
: 
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woocommerce_attribute_taxonomies: ✔
woocommerce_downloadable_product_permissions: ✔
woocommerce_order_items: ✔
woocommerce_order_itemmeta: ✔
woocommerce_tax_rates: ✔
woocommerce_tax_rate_locations: ✔
woocommerce_shipping_zones: ✔
woocommerce_shipping_zone_locations: ✔
woocommerce_shipping_zone_methods: ✔
woocommerce_payment_tokens: ✔
woocommerce_payment_tokenmeta: ✔

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iThemes Security: by iThemes – 6.1.1
Duplicator: by Snap Creek – 1.1.34
Exit Notifier: by Curtis V. Schleich – 1.3.1
Improved Include Page: by Marios Alexandrou – 1.0
Quform: by ThemeCatcher – 1.8.0
Collapse-O-Matic: by twinpictures
baden03 – 1.7.3

Post Expirator: by Aaron Axelsen – 2.1.4
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Revolution Slider: by ThemePunch – 4.6.0
Timed Content: by David Artiss – 1.2.4
The Events Calendar Category Colors: by Andy Fragen
Barry Hughes – 4.6.4

The Events Calendar: by Modern Tribe
Inc. – 4.4.3

U-Design WooCommerce Integration: by Andon – 1.0.1
WooCommerce Checkout Manager: by Visser Labs – 4.1
WooCommerce Customer/Order CSV Export: by SkyVerge – 3.9.1 – 4.1.4 is available
WooCommerce Grid / List toggle: by jameskoster – 1.1.0
WooCommerce Menu Cart: by Jeremiah Prummer
Ewout Fernhout – 2.5.8.1

WooCommerce Product Details Customiser: by jameskoster – 0.2.0
WooCommerce: by WooThemes – 2.6.14
WooSidebars: by WooThemes – 1.4.3
Yoast SEO: by Team Yoast – 4.4
WP-PageNavi: by Lester 'GaMerZ' Chan – 2.91

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### WC Pages ###

Shop Base: #5029 - /training/shop/
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Checkout: #5033 - /checkout/
My Account: #5036 - /my-account/

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simple (simple)
variable (variable)

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Version: 2.10.2
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### Templates ###

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u-design/woocommerce/checkout/form-billing.php
u-design/woocommerce/checkout/form-login.php
u-design/woocommerce/checkout/form-shipping.php
u-design/woocommerce/checkout/review-order.php
u-design/woocommerce/emails/customer-new-account.php
u-design/woocommerce/emails/customer-processing-order.php
u-design/woocommerce/global/form-login.php
u-design/woocommerce/myaccount/form-login.php version 2.2.6 is out of date. The core version is 2.6.0

: Learn how to update outdated templates