B737 MAX Captain reported an FMC database error which causes incorrect indication of the landing altitude indication and landing altitude reference bar.

Narrative

Landing Altitude Reference Bar and Landing Altitude Indicator Error in 737 MAX-8. I have now experienced two anomalies associated with the improper display of the Landing Altitude Reference Bar and the Landing Altitude Indication on the 737 MAX-8 aircraft. The Landing Altitude Indication (LAI) is an amber crosshatched area that shows the FMC-generated Landing altitude for the destination runway. It is displayed on the altimeter tape. The Landing Altitude Reference Bar (LARB) is a vertical line that is displayed just to the left of the altimeter on the PFD. It extends upward from the LAI showing height above touchdown; 0-500 ft.; amber; 500-1;000 ft.; white. Both are generated by the FMC and are displayed to warn the Pilots that they are close to the landing elevation. On (date) I operated Aircraft X from ZZZ-ZZZ1. While parked at the gate in ZZZ; and after loading our routing and completing all preflight duties; I noticed that the LAI and LARB were not displaying correctly on the PFD. While the altimeter was correctly showing an elevation of X;XXX ft. at the gate; the LARB was indicating that we were already 1;000 ft. in the air. The LARB extended downward on the display and the LAI was not visible because it was off the scale. In other words; the LAI amber crosshatched area was not shown just below the current elevation; as is normal when at the gate; and the LARB was indicating that we were already 1;000 ft. above the airport elevation. ZZZ Maintenance responded to our call and could not initially determine what was wrong. The problem did not trip any fault codes; so they tried reinitializing the IRSs; which had no effect. Next; they tried resetting FMC circuit breakers; which caused the LARB to disappear; but did not return the display to a normal state. In consultation with Company Manager on call; we finally tried reloading the FMC route through the MCDU. This step finally restored the display to a normal state. Apparently; something in the FMC database was corrupt; after we initially loaded the route; before noticing the problem; and was not corrected; until we re-loaded the route a second time. This was very concerning. Had we not noticed it; the LARB and LAI would not have displayed correctly on takeoff or landing; and could have led to a lot of confusion; especially if operating in IMC. The second time I have experienced this anomaly was while airborne; flying a 737 MAX 8 from ZZZ2 to ZZZ3 several months ago. After intercepting the ILS final approach course to Runway XX at 2;000 ft. altitude; we began slowing and configuring the aircraft. Just as we captured the glideslope; the LARB jumped up in elevation and indicated that we were just above 1;000 ft. above the landing elevation. The altimeter was still showing approximately 1;800 ft. and descending on the glideslope; but the LARB was displaying erroneous information. We executed a go-around and tried to figure out what was going on. I had the FO reload the ILS XX Approach into the FMC and basically start from scratch with our approach planning. The second approach to the ILS XX went normally with normal indications of the LARB and LAI. Again; it seems that there was some sort of corruption; or hiccup in the FMC database; that caused the erroneous indications. Thankfully; we were in VMC rather than IMC and the problem was visually evident. In conversation with several other pilots about this problem; I was told of at least one other event; while on approach; that was very similar to my experience in ZZZ3; but occurred at 6;000 ft.; while descending. I believe that this problem is worth noting and researching; that an alert to our Operations is warranted and that it is certainly worth warning other operators of the 737 MAX-8 about. The potential is there for serious cockpit confusion; depending on other conditions.