Attachment button disappears when clicking the icon when commenting during issue transition or comment edit

Issue Summary

This is reproducible on Data Center: yes

Steps to Reproduce

1. Do the transition when commenting during issue transition or comment edit, and try to upload attachments from transition screen.

Expected Results

You can upload attachments when commenting during issue transition or comment edit.

Actual Results

Attachment button will be disappeared by clicking the icon when commenting during issue transition or comment edit.

Notes

Jira 9.5 and 9.6 are not affected

Workaround

If necessary, upgrade to Jira 9.5 or 9.6
Disclaimer: these versions are not LTS versions and downgrading Jira version is not supported