Backslash "\" is missing in Visual Mode

Summary

The backslash "\" goes missing when in Visual Mode whereas appears normally in Text Mode. It goes missing when it is followed by some special characters. This causes users using Visual Mode or portals to be redirected to a broken link due to the missing backslash. Seems to be happening despite Rich Text Mode is enabled or disabled.

Environment

JIRA 7.8.0
Reported on previous versions as well

Expected Results

a a \ _ b b (without the spaces)

Actual Results

aa_bb

Workaround

• Use Text Mode
• Use Wiki Markup for Link (E.g.: [Link Title|URL-here])
• Use ASCII Code of the special character (E.g.: "_" replace with "&#95")