Shortcodes Ultimate No Longer Works in Terms & Conditions on Checkout

### Reproduction Steps

+ Install Shortcodes Ultimate and LifterLMS
+ In LifterLMS enable Terms and Conditions
+ In the Terms and Conditions Notice box add a Shortcodes Ultimate shortcode (in the user's case a 'label' shortcode)

### Expected Behavior

+ The shortcode renders and shows the label on the checkout page for the terms and conditions notice
+ This worked up until version LifterLMS 4.17.

### Actual Behavior

+ It shows the shortcode code not what it should be rendered as.

### Error Messages / Logs

+ Include any relevant error messages or log files
```

```

### System and Environment Information

System Report

```
Wordpress
-------------------------------------------

Home Url: https://.myliftersite.com
Site Url: https://myliftersite.com
Login Url: https://myliftersite.com/wp-login.php
Version: 5.7.2
Debug Mode: No
Debug Log: No
Debug Display: Yes
Locale: en_US
Multisite: No
Page For Posts: Not Set
Page On Front: Not Set
Permalink Structure: /%postname%/
Show On Front: posts
Wp Cron: Yes

Settings
-------------------------------------------

Version: 4.21.3
Db Version: 4.21.3
Course Catalog: Course Catalog (#6) [https://myliftersite.com/courses/]
Membership Catalog: Membership Catalog (#7) [https://.myliftersite.com/memberships/]
Student Dashboard: Dashboard (#9) [https://.myliftersite.com/dashboard/]
Checkout Page: Purchase (#8) [https://.myliftersite.com/purchase/]
Course Catalog Per Page: 9
Course Catalog Sorting: menu_order,ASC
Membership Catalog Per Page: 9
Membership Catalog Sorting: menu_order
Site Membership: Not Set
Courses Endpoint: my-courses
Edit Endpoint: edit-account
Lost Password Endpoint: lost-password
Vouchers Endpoint: redeem-voucher
Autogenerate Username: yes
Password Strength Meter: yes
Minimum Password Strength: strong
Terms Required: yes
Terms Page: Sample Page (#2) [https://.myliftersite.com/sample-page/]
Checkout Names: required
Checkout Address: required
Checkout Phone: optional
Checkout Email Confirmation: yes
Open Registration: yes
Registration Names: required
Registration Address: optional
Registration Phone: hidden
Registration Voucher: optional
Registration Email Confirmation: no
Account Names: required
Account Address: required
Account Phone: optional
Account Email Confirmation: yes
Confirmation Endpoint: confirm-payment
Force Ssl Checkout: no
Country: US
Currency: USD
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Decimals: 2
Trim Zero Decimals: no
Recurring Payments: yes
Email From Address: team+sandbox@lifterlms.com
Email From Name: A LifterLMS Sandbox
Email Footer Text:
Email Header Image:
Cert Bg Width: 800
Cert Bg Height: 616
Cert Legacy Compat: no

Constants
-------------------------------------------

LLMS_REMOVE_ALL_DATA: undefined
LLMS_REST_DISABLE: undefined
LLMS_SITE_FEATURE_RECURRING_PAYMENTS: undefined
LLMS_SITE_IS_CLONE: undefined

Gateways
-------------------------------------------

Stripe: Enabled
Stripe Test Mode: Enabled
Stripe Logging: no
Stripe Order: 1
Manual: Enabled
Manual Logging: no
Manual Order: 1

Server
-------------------------------------------

Mysql Version: 5.7.34
Php Curl: Yes
Php Default Timezone: UTC
Php Fsockopen: Yes
Php Max Input Vars: 5000
Php Max Upload Size: 512 MB
Php Memory Limit: 256M
Php Post Max Size: 1024M
Php Soap: Yes
Php Suhosin: No
Php Time Limt: 30
Php Version: 7.3.28
Software: Apache/2.4.46 (Unix) OpenSSL/1.1.1
Wp Memory Limit: 256M

Browser
-------------------------------------------

HTTP USER AGENT: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.77 Safari/537.36

Theme
-------------------------------------------

Name: Twenty Nineteen
Version: 2.0
Themeuri: https://wordpress.org/themes/twentynineteen/
Authoruri: https://wordpress.org/
Template:
Child Theme: No
Llms Support: No

Plugins
-------------------------------------------

LifterLMS: 4.21.3
LifterLMS Groups: 1.0.0-beta.10
LifterLMS Stripe Payment Gateway: 5.3.1
Shortcodes Ultimate: 5.10.0
User Switching: 1.5.7

Integrations
-------------------------------------------

BbPress: No
BuddyPress: No
LifterLMS Groups: Yes

Template Overrides
-------------------------------------------

```

This issue has be recreated:
+ [X] Locally
+ [X] On a staging site
+ [X] On a production website
+ [X] With only LifterLMS and a default theme

### Browser, Device, and Operating System Information

+ Browser name and version
+ Operating System name and version
+ Device name and version (if applicable)

HS-168178