Details of your operating system and version of Adobe Illustrator
Windows 10 Pro (1809) & Mac OSX 10.14.6
Illustrator 24.0.1 (64-bit) and older

The steps you were taking when you experienced the issues
Opening a standard EPS file which follows the Adobe EPS specification as mentioned in https://www.adobe.com/content/dam/acom/en/devnet/actionscript/articles/5002.EPSF_Spec.pdf (e.g. EPS produced by Affinity Designer, InkScape, QuarkXPress, etc.).

Your expected result
Illustrator should show the correct bounding box (artboard) as defined in the EPS header. The following minimum requirements are set out on page 6 of the specification linked above: »An application importing an EPS file must parse the EPS file for DSC comments and extract at least the bounding box and resource dependencies of the EPS file.«

Your actual result
Illustrator does not show the correct bounding box as defined in the EPS header. Illustrator instead shows the bounding box used in the last opened file.