This is a problem that impacts AACR2 records, including a significant quantity of e-resources, government and vendor supplied bibliographic records>

Punctuation between subfields is treated as part of the subfield itself, causing irregularities in the display of several fields.

The way Vega removes the $h [GMD] from the MARC 245 field, and $b is present, the ISBD punctuation is also removed. {a [h] : b} becomes {a b}, some examples {a [h] / c} becomes {a } the : or / following the $h is added to the Genre field

According to ISBD rules the colon preceding the additional title information is part of that area of the record, not the material designation or title proper.
Correct:

Title : Subtitle / author
Genre: [electronic resource]

Incorrect
Title Subtitle
Genre: [electronic resource] :

e.g., Creedence Clearwater revisited $h [sound recording] : $b extended versions
→

Creedence Clearwater revisited extended versions

The punctuation should be retained:

Creedence Clearwater revisited : extended versions