Well, you may try:
1) Try to use some new versions e.g 4.5.x, 4.6 or even 4.7.x if your subscription allows this. Mind you, when you purchase the license of the product, you are eligible to use the version/fixes that would be released in the next whole year. Please carefully open your license file into notepad and check the subscription expiry date. Now, try to use/download the version (from the site) that should be released before your subscription expiry date and after your version 4.3.x. It is quite possible that it is bug in older version like 4.3 and was already fixed in later versions e.g 4.6.x, 4.7.x etc, I am not sure about it though.
2) If the above process/method does not work for you, then, I am afraid there is no way but to upgrade your subscription to use latest versions/fixes. For this you may contact Sales/Purchase team.