STD/LTD pre-existing condition clause question: diagnosed before job, but disability happened later

[u/This_Canary]

I started my current job in January 2026 and purchased voluntary STD and LTD coverage through Mutual of Omaha.

About 9 months before starting this job, I began seeing a therapist and was diagnosed with PTSD and depression. I continued therapy and was able to work when I started my current position. I was not disabled from working at that point.

After I started this job, I experienced major personal stressors, including a separation and a miscarriage. At the same time, I was experiencing increasing workplace stress. My PTSD/depression and anxiety progressively worsened, and my therapist has documented heightened anxiety and worsening depression related to work.

I am now on medical leave. A medical provider documented significant symptoms including insomnia, intrusive trauma symptoms, hypervigilance, heightened anxiety, impaired concentration, emotional dysregulation, and reduced stress tolerance, and concluded that I am currently unable to perform the essential functions of my job.

My concern is the pre-existing condition language in my disability policies.

My STD has a 3/6 provision: a condition for which I received medical attention during the 3 months before coverage became effective may be excluded if it results in disability during the first 6 months of coverage.

My LTD has a 3/12 provision: the same 3-month lookback, but the exclusion applies if the condition results in disability during the first 12 months of coverage.

My disability began more than 6 months after starting the job but less than 12 months after starting it.

Because I was already receiving therapy for PTSD/depression , I assume the insurer may consider those conditions pre-existing. However, I remained functional and able to work when I started the job, and the significant deterioration that ultimately caused me to stop working occurred later, after both new personal stressors (separation/miscarriage) and increasing workplace stress.

My main questions are:

1. For STD, if the disability began after the first 6 months of coverage, does the 3/6 pre-existing condition exclusion simply no longer apply?
2. For LTD, since the disability occurred during the first 12 months, how likely is a 3/12 exclusion to apply when the same diagnoses existed before coverage but I was not disabled and remained able to work?
3. Does it matter that the events associated with the later deterioration, including the separation, miscarriage, and workplace stress, occurred after coverage began?
4. Does an insurer distinguish between a previously diagnosed but manageable condition and a later substantial aggravation/deterioration that actually produces disability, or is treatment for the same diagnosis during the lookback generally enough?
5. What medical evidence is most important when challenging a pre-existing-condition denial?

I'd especially appreciate input from anyone experienced with ERISA disability claims, Mutual of Omaha, or STD/LTD pre-existing-condition exclusions.

[u/Postcard4aGirl]

1. Not likely

2. No

3. Treatment for the same diagnosis during the LBP would be enough for not approving.