Firefox 68 having issue with Ad Hoc drop down list selection

So the solution is as follows: 

1. Log in as an administrator with access to the "default" theme you use to download it. 
2. Click View > Repository and expand the Themes folder if necessary. 
3. Right-click the theme folder you want to download and select Export.
4. The server prompts you to save the file named <theme-name>.zip. Save it anywhere on your computer. 
5. Use an archiving or compression utility to extract the files from the ZIP file and save them on your computer. 
6. Find a file controls.css (/themes/default/controls.css) 

7. Open with any text editor, jump to line 2016 (might differ) to find the following block

   .toolbar .dropList {      width:auto;      margin-top: 4px;      margin-right: 8px;      margin-left: 8px; }

   change it to

   .toolbar .dropList {      width:auto;      margin-top: 4px;      margin-right: 8px;      margin-left: 8px;      display: block; }

8. Create a zip archive with the theme files. 
9. Go to jasper server > manage > server settings > import > choose the archive with the theme > tick include themes option and press import. 
10. Refresh your browser page ctrl+f5. Restart of application server might be required if you see no changes. 

If you are already using theme modifications, just add the following to your overrides_customs.css:

.toolbar .dropList { display: block; }