I have homebrewed a subclass (https://www.dndbeyond.com/subclasses/944845-arcane-archer-remastered), and everything seems to work fine, except for the snippet for its Elemental Arrow option, which is simply missing, as it can be seen on this character sheeet: https://www.dndbeyond.com/profile/Semako/characters/55244226

The snippet is entered exactly like the snippets for the other Arcane Shots both in the option and the action corresponding to the option, its code is

Choose either acid, cold, fire, lightning or thunder. The arrow's effects depend on the chosen element:

<ul>
<li><em>Acid</em>: The target takes <strong>4d4</strong> acid damage and must make a Dexterity saving throw, or be covered in acid for 1 minute and take <strong>2d4</strong> acid damage at the start of each of its turns. [10th] <strong>+2d4</strong> acid damage on hit, <strong>+1d4</strong> residual acid damage. [18th] <strong>+2d4</strong> acid damage on hit, <strong>+1d4</strong> residual acid damage</li>
<li><em>Cold</em>: The target takes an additional <strong>2d8</strong> cold damage and must make a Constitution saving throw or has its movement speed halved until the end of its next turn. [10th] <strong>+1d8</strong> cold damage on hit. [18th] <strong>+1d8</strong> cold damage on hit.</li>
<li><em>Fire</em>: The target and all creatures within 10 feet of it must make a Dexterity saving throw, taking 4d6 fire damage on a failure or half as much on a success. [10th] <strong>+2d6</strong> fire damage. [18th] <strong>+2d6</strong> fire damage</li>
<li><em>Lightning</em>: The target and all creatures within the path of the arrow must succeed on a Dexterity saving throw, taking 4d6 lightning damage on a failure or half as much on a success. [10th] <strong>+2d6</strong> lightning damage. [18th] <strong>+2d6</strong> lightning damage</li>
<li><em>Thunder</em>: The target takes an additional <strong>2d8</strong> thunder damage and must make a Constitution saving throw or is pushed up to 15 feet away. [10th] <strong>+1d8</strong> thunder damage on hit. [18th] <strong>+1d8</strong> thunder damage on hit.</li></ul>

I don't get what the problem is, as the other snippets work without issues. Can you help me?

So  is it not possible to include a list within a snippet?

<b>, <i> and <u> also work.

I managed to test a snippet with <ul> and <ol> (in a custom action, which strips away html tags from a snippet after you refresh the page so it's only good for testing) and it showed the elements, but didn't generate bullets or list-numbers, so not really any point to using them.

Then I will rewrite the snippet's HTML, using line-breaks and the HTML code for the bullet point symbol • •  or  ● ● instead. Thank you :)

I changed the snipped, removing the list:

Choose either acid, cold, fire, lightning or thunder. The arrow's effects depend on the chosen element:<br><br>
<strong>&bull;</strong> <em>Acid</em>: The target takes <strong>4d4</strong> acid damage and must make a Dexterity saving throw, or be covered in acid for 1 minute and take <strong>2d4</strong> acid damage at the start of each of its turns. [10th] <strong>+2d4</strong> acid damage on hit, <strong>+1d4</strong> residual acid damage. [18th] <strong>+2d4</strong> acid damage on hit, <strong>+1d4</strong> residual acid damage<br>
<strong>&bull;</strong><em>Cold</em>: The target takes an additional <strong>2d8</strong> cold damage and must make a Constitution saving throw or has its movement speed halved until the end of its next turn. [10th] <strong>+1d8</strong> cold damage on hit. [18th] <strong>+1d8</strong> cold damage on hit.<br>
<strong>&bull;</strong><em>Fire</em>: The target and all creatures within 10 feet of it must make a Dexterity saving throw, taking 4d6 fire damage on a failure or half as much on a success. [10th] <strong>+2d6</strong> fire damage. [18th] <strong>+2d6</strong> fire damage<br>
<strong>&bull;</strong><em>Lightning</em>: The target and all creatures within the path of the arrow must succeed on a Dexterity saving throw, taking 4d6 lightning damage on a failure or half as much on a success. [10th] <strong>+2d6</strong> lightning damage. [18th] <strong>+2d6</strong> lightning damage<br>
<strong>&bull;</strong><em>Thunder</em>: The target takes an additional <strong>2d8</strong> thunder damage and must make a Constitution saving throw or is pushed up to 15 feet away. [10th] <strong>+1d8</strong> thunder damage on hit. [18th] <strong>+1d8</strong> thunder damage on hit.

 And it still does not show up. What can be the problem then?