Hasan

very interesting observation.
I had been assuming that inverter would have switched to PV and keep abnormal supply from grid out of the system, but obviously it is the other way around.
That one reason more to keep my two servers under UPS with voltage regulator.
Originally I had planned to sell UPS and 4 x 150Ah batteries once inverter and PV was installed. Then I realized that it was nice to be able to be able work on inverter and DB board / earth leakage without worrying about supply to servers (I have UPS under inverter). Then some faulty appliance tripped the earth leakage and it became obvious I still needed the UPS. Eventually we had a very long power outage and by early morning inverter batteries were out and PV power was insufficient for about one hour: at that point UPS took over and saved the day: it's great peace of mind to know that UPS can still run servers for >9hours after inverter  is out.

I had a similar problem. Every now and again I noticed that the PV power dropped quite a lot for a few minutes at a time while the skies are clear and the sun shines bright. My only thought was that one of these huge birds in our area (I don't know what they are, but they are huge and so are their no.2's) camped out on a panel and caused partial shading - as you know partial shading / covering one cell has a huge impact when you have only 1 serial string of panels. It is quite easy to get on to the roof and usually whenever I noticed this behavior I would grab the ladder and go check the panels, but to my surprise I never spotted a bird, there was no partial shading and no no.2's covering enough of any of the cells to cause the drop in PV, so I always thought that it might have been a bird and it flew away before I got to the panels.
Then about a month ago on the Sunday morning I walked through the garage again and noticed the same behavior - a drop in inverter fan speed usually indicates lower PV power. I grabbed the ladder again and again found nothing out of the ordinary on any of the panels, but this time when I got back to the inverter the PV was still low. 
I then switched on the PC and checked the settings and the logs and then spotted the "Grid frequency upper limit reached" warning and noticed that the grid frequency was at 50.2 Hz and the upper limit was set to 50.1 Hz. Needless to say, as soon as I've changed the upper limit to 50.3 Hz, the PV power shot up and the inverter started feeding to the grid again.
The verdict - the lower overall grid load on the Sunday morning caused the grid frequency to rise which caused the inverter to stop feeding back.

I've had a similar experience a few days after I've installed my infini about a year ago. It was a Saturday afternoon and we had loadshedding. It was after 16:00 and PV generation has dropped to about 1KW at that time.  My wife was busy vacuuming floors and at least 2 TVs, fridge(s) and / or freezer as well as other parasitic loads like dstv / electric fence / PC etc. etc. were running from the inverter. Without thinking about loadshedding, I started vacuuming the car at the same time. After a few minutes my vacuum cleaner stopped working and I thought it was the intermittent lead connection again and switched it off, checked and fiddled the lead and switched it back on again, vacuumed some more and a few minutes later it died again, I fiddled again and it started working again. A few minutes later it stopped again and then I investigated some more. I noticed that the time on the digital clock in the garage was reset and went to ask my wife if the power went off while she was vacuuming and she confirmed it happened a few times. I then realized that we've probably overloaded the inverter and it self-recovered. Then I checked the load on the inverter and saw that while she vacuumed the total load was about 2.2KW and when I started my vacuum cleaner as well it went to about 3.7KW and after a few minutes the inverter tripped and about a minute later everything started up again.
I have also recently tested the overload capability while the grid was available - I loaded the inverter with a total load of just under 6KW for about 10 minutes without any issues.

just to follow up:
My understanding is that your inverter sends your MONITORED DEVICE INFORMATION to the software:

Then you may adjust PARAMETERS SETTINGS within those MONITORED DEVICE INFORMATION parameters (I did not try if software accepts any parameter outside range but I would imagine not and in any case I do not suggest to anyone to attempt that):

Obviously the closer to the preset factory settings in DEVICE INFORMATION and the happier your inverter should be.
For example I was having trouble with min and max AC INPUT FREQUENCY. Although device supports a range between 40 and 55Hz I found that altering the range between 47.6 and 50.4Hz was perfectly sufficient for me.
I saw no point in widen the range further because wider ranges might have negative effect on appliances and even trigger earth leakage to trip.