Problem with stock – negative!

Hello! I have a problem with woocommerce since I opened the shop. I have consulted with 3 experts and no one gives with the error.

At the store, I have created products (is the same if they are simple or variable). If do not put it stock management, there is no problem. When active, if for example I have 100 of such a product, if someone buys one, it puts me in – 1 and sold out. If you buy 2, – 2. Even if you have 100, in the historical order puts the stock of product X has gone from 0 to – 2.

We have been reviewing the database and all good. If I put that product has 10 in stock, is recorded thus in the database.

I have disabled all of the plugins.

Obviously all woocommerce settings is OK.

I have deleted while woocommerce (including the database) and reinstalled.

Right now I have the products without stock management and they work well, but that is not a long-term solution because I have to be always aware of mark the product as sold out when they buy the latest.

I’m sorry, my English is not very good.

Thank you!

### WordPress Environment ###

Home URL: https://mlcshop.es
Site URL: https://mlcshop.es
WC Version: 2.6.4
Log Directory Writable: ?
WP Version: 4.6.1
WP Multisite: –
WP Memory Limit: 256 MB
WP Debug Mode: –
WP Cron: ?
Language: es_ES

### Server Environment ###

Server Info: Apache
PHP Version: 5.6.24
PHP Post Max Size: 100 MB
PHP Time Limit: 18000
PHP Max Input Vars: 50000
cURL Version: 7.29.0
NSS/3.19.1 Basic ECC

SUHOSIN Installed: –
Max Upload Size: 100 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Publicación remota: ?
Obtención remota: ?

### Database ###

WC Database Version: 2.6.4
: 
woocommerce_sessions: ?
woocommerce_api_keys: ?
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: ?
MaxMind GeoIP Database: ?

### Active Plugins (10) ###

Contact Form 7: por Takayuki Miyoshi – 4.5.1
PayPal Express Checkout for WooCommerce: por wpgateways – 1.1.7
Genesis eNews Extended: por Brandon Kraft – 2.0.2
Jetpack por WordPress.com: por Automattic – 4.3.1
Simple Social Icons: por Nathan Rice – 1.0.13
WooCommerce: por WooThemes – 2.6.4
WP From Email: por Skullbit.com – 1.1
WP Instagram Widget: por Scott Evans – 1.9.8
Modo de Mantenimiento WP: por Designmodo – 2.0.8
Estadísticas de WP: por Mostafa Soufi & Greg Ross – 10.3

### Settings ###

Force SSL: –
Currency: EUR (€)
Currency Position: right
Thousand Separator: .
Decimal Separator: ,
Number of Decimals: 2

### API ###

API Enabled: ?

### WC Pages ###

Base de la tienda: #1950 - /tienda/
Carrito: #1342 - /carro/
Finalizar compra: #1343 - /finalizar-comprar/
Mi cuenta: #1344 - /mi-cuenta/

### Taxonomies ###

Product Types: external (external)
grouped (grouped)
simple (simple)
variable (variable)

### Theme ###

Name: Coastal
Version: 2.2.0
Author URL: https://stnsvn.com
Child Theme: ?
Parent Theme Name: Genesis
Parent Theme Version: 2.4.2
Parent Theme Author URL: https://www.studiopress.com/
WooCommerce Support: ?

### Templates ###

Overrides: coastal/woocommerce/emails/customer-note.php