“Read more” with custom excerpt

Hello,

For some posts I need to use custom excerpts in order to keep some formatting tags (mainly <br>) that are not in the main post text.

Problem is, in such cases, the word count limit is not applied and the “Read more” link doesn’t display and I rather simply get the whole text block I’ve added in the custom excerpt box.

Is there a way at least to force the “Read more” link?
Or, otherwise, to respect line breaks from the original text (so that I keep using the original texts instead of custom excerpts)?

Thanks!