A Study in Participants With Sarcoidosis-associated Pulmonary Hypertension (SAPH) to Assess the Efficacy and Safety of Oral Selexipag

Main Inclusion Criteria: * Confirmed diagnosis of sarcoidosis as per American Thoracic Society (ATS) criteria * Sarcoidosis-associated precapillary PH, confirmed by RHC (at rest) within 90 days prior to randomization. * PH severity according to modified WHO FC II-IV at Screening and randomization; participants in WHO FC IV must be in a stable condition and able to perform a 6MWT. * Either not receiving treatment with PH-specific treatment or oral PH-specific monotherapy (ie, riociguat or PDE5i or ERA); if on oral PH-specific monotherapy then treatment had to be stable (ie, no introduction of new therapies or changes in dose) for at least 90 days prior to both and the RHC qualifying for enrollment and randomization * Stable sarcoidosis treatment regimen, ie, no new specific anti-inflammatory treatment for sarcoidosis for at least 90 days, and stable dose(s) for at least 30 days prior to both the RHC qualifying for enrollment and randomization * 6-minute walk distance (6MWD) greater than or equal to (\>=) 50 meters both at Screening and at the time of randomization. Participants can use their usual walking aids during the test (example, cane, crutches). The same walking aid should be used for all 6-minute walk test (6MWTs). Walkers are not allowed * Forced Vital Capacity (FVC) greater than (\>) 50 percent (%) and Forced Expiratory Volume (in 1 second) (FEV1) \> 50% of predicted at Screening * Diffusing capacity of the lung for carbon monoxide (DLCO) \>= 40% of predicted. If DLCO less than (\<) 40% of predicted, the extent of emphysema should not be greater than that of fibrosis as assessed by high resolution computerized tomography (CT) scan * Women of childbearing potential must have a negative pregnancy test at screening and randomization, must agree to undertake monthly urine pregnancy tests, and to practice an acceptable method of contraception and agreeing to remain on an acceptable method while receiving study intervention and until 30 days after last dose of study intervention * A woman only using hormonal contraceptives must have been using this method for at least 30 days prior to randomization Main Exclusion Criteria: * PH due to left heart disease (PAWP \>15 mmHg). * History of left heart failure (LHF) as assessed by the investigator including cardiomyopathies, and cardiac sarcoidosis, with a left ventricular ejection fraction (LVEF) \<40%. * Treatment with prostacyclin, prostacyclin analogues or IP receptor agonists (ie, selexipag) within 90 days prior to randomization and/or prior to the RHC qualifying for enrollment, except those given at vasodilator testing during RHC. * SBP \<90 mmHg at Screening or at randomization. * Included on a lung transplant list or planned to be included until Visit 6 / Week 39. * Change in dose or initiation of new diuretics and/or calcium channel blockers within 1 week prior to RHC qualifying for enrollment. * Any condition for which, in the opinion of the investigator, participation would not be in the best interests of the participant (eg, compromise well-being), or that could prevent, limit, or confound the protocol-specified assessments. * Any acute or chronic impairment that may influence the ability to comply with study requirements such as to perform RHC, a reliable and reproducible 6MWT, or lung function tests. * Any other criteria as per selexipag Summary of Product Characteristics (SmPC)