Reason might be the spend is not upto the level to reach threshold amount for exact stats.

Google doesn't disclose the amount, but my guess is that it is below USD $100. Could be an all-time figure, or could be based on per month spend.

once you have an active campaign and it starts running, irrespective o f the amount could be as low a s 1$ a day like i do sometimes when i just want to be using keyword tool, you keep  getting full details in exact volumes, once you your ads start running in 48 hours time you should have access to full exact volumes.. my experience  ps.. and irrespective of the ads, i only do universal apps installs.. its sad but i called a few times wasted my credit on google support and its sad that they employ people that dont even understand the full tools they have and how it works (mostly indian people i talked with, no offence pls) but i saw they didnt know how google ads keyword planner to be exact works, i had to guide them like a baby. when they should be giving me support. one told me  i need to create a website campaign before keyword planner would work. i hav never made a website campgin in this account and i have been usingkeyword planner exact volume for years every day to do my research.. anothe rkept asking me the keyword i was puttung an di kept saying it doesnt matter the keyword i pu tthe issue was i am getting range value instead of exact value being ac active advertiser....Google ads need to spend more to train their support staff. i was really disappointed!