Equation Editor unexpectedly appears to merge separate inline equations and any content between them when editing

[brichwin]

Description

When editing a sentence containing multiple equations, the Equation Editor exhibits unexpected behavior that appears to merge separate equations.

A video demonstrating the issue is available: Video: Equation Editor unexpectedly merges separate inline equations and any content between them when editing (2 minutes)

Steps to Reproduce

1. Type the following sentence in Word, using the Equation Editor for the mathematical expressions:
   "The expressions $4+5$ and $6+4$ are equivalent."

2. Place the cursor at the end of the first expression (after "5")

3. Press the backspace key

Expected Behavior

• When backspacing in the first expression, the Equation Editor should remain confined to just that expression
• The second expression should remain separate and independent
• Moving through the text should treat each expression as distinct

Actual Behavior

• Pressing backspace causes the Equation Editor to unexpectedly expand and merge both expressions
• The Equation Editor grows to encompass everything from the first expression through the second expression, including the text between them
• When navigating:
  • With cursor in either expression: Both expressions and intervening text are shown as merged in the editor
  • With cursor between expressions (e.g., in the word "and"): Equation Editor disappears entirely

Impact

This behavior:

• Makes it difficult to edit individual expressions
• Creates confusion about which parts of the text are part of the equation
• Disrupts the normal flow of document editing
• Could lead to unintended changes when trying to make simple corrections

Tested Version Information

Windows OS

OS Version:
-- OS Name: Microsoft Windows 11 Enterprise
-- Version: 10.0.22621 Build 22621
-- Locale: United States
Microsoft Word Version:
-- Microsoft 365 Apps for enterprise
-- Version 2410 (Build 18129.20158 Click-to-Run) Current Channel